Post on 12-Mar-2020
transcript
Singly Linked Lists
2
Objectives
In this session, you will learn to:Identify the features of linked lists
Implement a singly-linked list
Insertion in a linked List
Deletion from a Linked List
Traversing a Linked list
3
Suppose you have to write an algorithm to generate andstore all prime numbers between 1 and 10,00,000 anddisplay them.
How will you solve this problem?
Linked List
4
Consider the following algorithm, which uses an array tosolve this problem:1. Set I = 0
2. Repeat step 3 varying N from 2 to 1000000
3. If N is a prime numbera. Set A[I] = N // If N is prime store it in an array
b. I = I + 1
4. Repeat step 5 varying J from 0 to I-1
5. Display A[J] // Display the prime numbers // stored in the array
Linked List (Contd.)
5
What is the problem in this algorithm?The number of prime numbers between 1 and 10,00,000 is notknown. Since you are using an array to store the primenumbers, you need to declare an array of arbitrarily large sizeto store the prime numbers.
Disadvantages of this approach, suppose you declare an arrayof size N:
If the number of prime numbers between 1 and 10,00,000is more than N then all the prime numbers cannot bestored.
If the number of prime numbers is much less than N, a lotof memory space is wasted.
Linked List (Contd.)
6
Thus, you cannot use an array to store a set of elements ifyou do not know the total number of elements in advance.
How do you solve this problem?By having some way in which you can allocate memory as andwhen it is required.
Linked List (Contd.)
7
When you declare an array, a contiguous block of memory is allocated.
Let us suppose you declare an array of size 10 to store first 10 primenumbers.
If you know the address of the first element in the array you cancalculate the address of any other elements as shown:
Address of the first element + (size of the element × index of the element)
0123456789
100010021004
1018
10081010101210141016
1006One contiguous block ofmemory allocated forthe array to store 10elements.
Memory representation
Dynamic Memory Allocation
8
When memory is allocated dynamically, a block of memoryis assigned arbitrarily from any location in the memory.
Therefore, unlike arrays, these blocks may not becontiguous and may be spread randomly in the memory.
0123456789
100010021004
1018
10081010101210141016
1006One contiguous block ofmemory allocated forthe array to store 10elements.
Memory representation
Dynamic Memory Allocation (Contd.)
9
Let us see how this happens by allocating memorydynamically for the prime numbers.
Allocate memory for 2 Memory allocated for 221002
Memory representation
Dynamic Memory Allocation (Contd.)
10
Let us see how this happens.
Allocate memory for 3 Memory allocated for 32
3
1002
1036
Memory representation
Dynamic Memory Allocation (Contd.)
11
Let us see how this happens.
Allocate memory for 5 Memory allocated for 52
3
51008
1002
1036
Memory representation
Dynamic Memory Allocation (Contd.)
12
Let us see how this happens.
Allocate memory for 7 Memory allocated for 72
3
5
71020
1008
1002
1036
Memory representation
Dynamic Memory Allocation (Contd.)
13
Let us see how this happens.
Allocate memory for 11 Memory allocated for 112
3
5
7
111030
1020
1008
1002
1036
Memory representation
Dynamic Memory Allocation (Contd.)
14
If you know the address of the first element, you cannotcalculate the address of the rest of the elements.
This is because, all the elements are spread at randomlocations in the memory.
2
3
5
7
111030
1020
1008
1002
1036
Memory representation
To access any element, you need to know its address.
Dynamic Memory Allocation (Contd.)
15
Therefore, it would be good if every allocated block ofmemory contains the address of the next block insequence.
This gives the list a linked structure where each block islinked to the next block in sequence.
2
3
5
7
11
1036
1008
1020
1030
1030
1020
1008
1036
1002
Memory representation
Dynamic Memory Allocation (Contd.)
16
You can declare a variable, START, that stores the addressof the first block.
You can now begin at START and move through the list byfollowing the links.
START
1030
1020
1008
1036
1002 2
3
5
7
11
1036
1008
1020
1030
Memory representation
An example of a data structure that implements thisconcept is a linked list.
Dynamic Memory Allocation (Contd.)
17
Linked list:Is a dynamic data structure.
Allows memory to be allocated as and when it is required.
Consists of a chain of elements, in which each element isreferred to as a node.
Defining Linked Lists
18
Defining Linked Lists (Contd.)
Data Link
Node
A node is the basic building block of a linked list.
A node consists of two parts:Data: Refers to the information held by the node
Link: Holds the address of the next node in the list
19
10Data 3352 10Data 5689 10Data 1012 10Data
2403 3352 5689 1012
All the nodes in a linked list are present at arbitrary memorylocations.
Therefore, every node in a linked list has link field thatstores the address of the next node in sequence.
The last node in a linked list does not point to any othernode. Therefore, it points to NULL.
NULL
Defining Linked Lists (Contd.)
20
To keep track of the first node, declare a variable/pointer,START, which always points to the first node.
When the list is empty, START contains null.
START
10Data 3352 10Data 5689 10Data 1012 10Data
2403 3352 5689 1012
NULL
Defining Linked Lists (Contd.)
21
HOW TO CREATE A NODE
struct node
{
int info;
struct node *next;
};
struct node *new1;new1=(struct node*) malloc(sizeof(struct node))
new1->info=3;
new1->next=NULL;
22
A new node can be inserted at any of the following positionsin the list:
Beginning of the list
End of the List
At specific position
In a Sorted Linked List
Inserting a Node in a Singly-Linked List (Contd.)
23
Refer to the given algorithm toinsert a node at the end of thelinked list.
1. Allocate memory for the newnode.
2. Assign value to the data field ofthe new node.
3. If START is NULL, then (If thelist is empty):a. Make START point to the
new node.b. Make LAST point to the
new node.c. Go to step 6.
4. Make the next field of LASTpoint to the new node.
5. Mark the new node as LAST.
6. Make the next field of the newnode point to NULL.
Inserting a Node a Singly-Linked LIST
24
Consider that the list is initiallyempty.
1. Allocate memory for thenew node.
2. Assign value to the datafield of the new node.
3. If START is NULL, then (Ifthe list is empty):a. Make START point to
the new node.b. Make LAST point to
the new node.c. Go to step 6.
4. Make the next field ofLAST point to the newnode.
5. Mark the new node asLAST.
6. Make the next field of thenew node point to NULL.
START = NULL
LAST = NULL
Insert a prime number 2.
Inserting a Node in a Singly-Linked List(Contd.)
25
1. Allocate memory for thenew node.
2. Assign value to the datafield of the new node.
3. If START is NULL, then(If the list is empty):a. Make START point
to the new node.b. Make LAST point to
the new node.c. Go to step 6.
4. Make the next field ofLAST point to the newnode.
5. Mark the new node asLAST.
6. Make the next field ofthe new node point toNULL.
START = NULL
Insert a prime number 2.
Inserting a Node in a Singly-Linked List(Contd.)
26
102
START = NULL
LAST = NULL
1. Allocate memory for thenew node.
2. Assign value to the datafield of the new node.
3. If START is NULL, then(If the list is empty):a. Make START point
to the new node.b. Make LAST point to
the new node.c. Go to step 6.
4. Make the next field ofLAST point to the newnode.
5. Mark the new node asLAST.
6. Make the next field ofthe new node point toNULL.
Inserting a Node in a Singly-Linked List(Contd.)
27
102
START = NULL
LAST = NULL
START
1. Allocate memory for thenew node.
2. Assign value to the datafield of the new node.
3. If START is NULL, then(If the list is empty):a. Make START point
to the new node.b. Make LAST point to
the new node.c. Go to step 6.
4. Make the next field ofLAST point to the newnode.
5. Mark the new node asLAST.
6. Make the next field ofthe new node point toNULL.
Inserting a Node in a Singly-Linked List(Contd.)
28
102
START LAST
LAST = NULL
1. Allocate memory for thenew node.
2. Assign value to the datafield of the new node.
3. If START is NULL, then(If the list is empty):a. Make START point
to the new node.b. Make LAST point to
the new node.c. Go to step 6.
4. Make the next field ofLAST point to the newnode.
5. Mark the new node asLAST.
6. Make the next field ofthe new node point toNULL.
Inserting a Node in a Singly-Linked List(Contd.)
29
102
START LAST
1. Allocate memory for thenew node.
2. Assign value to the datafield of the new node.
3. If START is NULL, then(If the list is empty):a. Make START point
to the new node.b. Make LAST point to
the new node.c. Go to step 6.
4. Make the next field ofLAST point to the newnode.
5. Mark the new node asLAST.
6. Make the next field ofthe new node point toNULL.
Inserting a Node in a Singly-Linked List(Contd.)
30
Insertion complete
102
START LAST
1. Allocate memory for thenew node.
2. Assign value to the datafield of the new node.
3. If START is NULL, then(If the list is empty):a. Make START point
to the new node.b. Make LAST point to
the new node.c. Go to step 6.
4. Make the next field ofLAST point to the newnode.
5. Mark the new node asLAST.
6. Make the next field ofthe new node point toNULL.
Inserting a Node in a Singly-Linked List(Contd.)
31
Insert a prime number 3.
102
START LAST
1. Allocate memory for thenew node.
2. Assign value to the datafield of the new node.
3. If START is NULL, then(If the list is empty):a. Make START point
to the new node.b. Make LAST point to
the new node.c. Go to step 6.
4. Make the next field ofLAST point to the newnode.
5. Mark the new node asLAST.
6. Make the next field ofthe new node point toNULL.
Inserting a Node in a Singly-Linked List(Contd.)
32
102
START LAST
Insert a prime number 3.
1. Allocate memory for thenew node.
2. Assign value to the datafield of the new node.
3. If START is NULL, then(If the list is empty):a. Make START point
to the new node.b. Make LAST point to
the new node.c. Go to step 6.
4. Make the next field ofLAST point to the newnode.
5. Mark the new node asLAST.
6. Make the next field ofthe new node point toNULL.
Inserting a Node in a Singly-Linked List(Contd.)
33
102
START
103
LAST
1. Allocate memory for thenew node.
2. Assign value to the datafield of the new node.
3. If START is NULL, then(If the list is empty):a. Make START point
to the new node.b. Make LAST point to
the new node.c. Go to step 6.
4. Make the next field ofLAST point to the newnode.
5. Mark the new node asLAST.
6. Make the next field ofthe new node point toNULL.
Inserting a Node in a Singly-Linked List(Contd.)
34
102
START
103
LAST
1. Allocate memory for thenew node.
2. Assign value to the datafield of the new node.
3. If START is NULL, then(If the list is empty):a. Make START point
to the new node.b. Make LAST point to
the new node.c. Go to step 6.
4. Make the next field ofLAST point to the newnode.
5. Mark the new node asLAST.
6. Make the next field ofthe new node point toNULL.
Inserting a Node in a Singly-Linked List(Contd.)
35
102
START
103
LAST
1. Allocate memory for thenew node.
2. Assign value to the datafield of the new node.
3. If START is NULL, then(If the list is empty):a. Make START point
to the new node.b. Make LAST point to
the new node.c. Go to step 6.
4. Make the next field ofLAST point to the newnode.
5. Mark the new node asLAST.
6. Make the next field ofthe new node point toNULL.
Inserting a Node in a Singly-Linked List(Contd.)
36
102
START
103
LASTLAST
1. Allocate memory for thenew node.
2. Assign value to the datafield of the new node.
3. If START is NULL, then(If the list is empty):a. Make START point
to the new node.b. Make LAST point to
the new node.c. Go to step 6.
4. Make the next field ofLAST point to the newnode.
5. Mark the new node asLAST.
6. Make the next field ofthe new node point toNULL.
Inserting a Node in a Singly-Linked List(Contd.)
37
Insertion complete
102
START
103
LAST
1. Allocate memory for thenew node.
2. Assign value to the datafield of the new node.
3. If START is NULL, then(If the list is empty):a. Make START point
to the new node.b. Make LAST point to
the new node.c. Go to step 6.
4. Make the next field ofLAST point to the newnode.
5. Mark the new node asLAST.
6. Make the next field ofthe new node point toNULL.
Inserting a Node in a Singly-Linked List(Contd.)
38
Insert a prime number 5.
102
START
103
LAST
1. Allocate memory for thenew node.
2. Assign value to the datafield of the new node.
3. If START is NULL, then(If the list is empty):a. Make START point
to the new node.b. Make LAST point to
the new node.c. Go to step 6.
4. Make the next field ofLAST point to the newnode.
5. Mark the new node asLAST.
6. Make the next field ofthe new node point toNULL.
Inserting a Node in a Singly-Linked List(Contd.)
39
102
START
103
LAST
Insert a prime number 5.
1. Allocate memory for thenew node.
2. Assign value to the datafield of the new node.
3. If START is NULL, then(If the list is empty):a. Make START point
to the new node.b. Make LAST point to
the new node.c. Go to step 6.
4. Make the next field ofLAST point to the newnode.
5. Mark the new node asLAST.
6. Make the next field ofthe new node point toNULL.
Inserting a Node in a Singly-Linked List(Contd.)
40
102
START
103 105
LAST
1. Allocate memory for thenew node.
2. Assign value to the datafield of the new node.
3. If START is NULL, then(If the list is empty):a. Make START point
to the new node.b. Make LAST point to
the new node.c. Go to step 6.
4. Make the next field ofLAST point to the newnode.
5. Mark the new node asLAST.
6. Make the next field ofthe new node point toNULL.
Inserting a Node in a Singly-Linked List(Contd.)
41
102
START
103 105
LAST
1. Allocate memory for thenew node.
2. Assign value to the datafield of the new node.
3. If START is NULL, then(If the list is empty):a. Make START point
to the new node.b. Make LAST point to
the new node.c. Go to step 6.
4. Make the next field ofLAST point to the newnode.
5. Mark the new node asLAST.
6. Make the next field ofthe new node point toNULL.
Inserting a Node in a Singly-Linked List(Contd.)
42
102
START
103 105
LAST
1. Allocate memory for thenew node.
2. Assign value to the datafield of the new node.
3. If START is NULL, then(If the list is empty):a. Make START point
to the new node.b. Make LAST point to
the new node.c. Go to step 6.
4. Make the next field ofLAST point to the newnode.
5. Mark the new node asLAST.
6. Make the next field ofthe new node point toNULL.
Inserting a Node in a Singly-Linked List(Contd.)
43
102
START
103 105
LASTLAST
1. Allocate memory for thenew node.
2. Assign value to the datafield of the new node.
3. If START is NULL, then(If the list is empty):a. Make START point
to the new node.b. Make LAST point to
the new node.c. Go to step 6.
4. Make the next field ofLAST point to the newnode.
5. Mark the new node asLAST.
6. Make the next field ofthe new node point toNULL.
Inserting a Node in a Singly-Linked List(Contd.)
44
Insertion complete
102
START
103 105
LAST
1. Allocate memory for the newnode.
2. Assign value to the data fieldof the new node.
3. If START is NULL, then (If thelist is empty):a. Make START point to the
new node.b. Make LAST point to the
new node.c. Go to step 6.
4. Make the next field of LASTpoint to the new node.
5. Mark the new node as LAST.
6. Make the next field of thenew node point to NULL.
Inserting a Node in a Singly-Linked List(Contd.)
45
ALGORITHM TO INSERT NODE AT END
Start=NULL
Algorithm InsertAtEnd()
{
1. Create node [(new1 = (struct node*)malloc(sizeof(struct node))]
2. Enter data [new1 -> info =d ata]
3.if(Start == NULL)
3.1 Last=new1
3.2 Start=new1
else
3.1 Last -> next = new1
3.2 Last = new1
4. Last ->next = NULL
}
1. Allocate memory for the new node.
2. Assign value to the data field of thenew node.
3. If START is NULL, then (If the list isempty):a. Make START point to the new
node.b. Make LAST point to the new node.c. Go to step 6.
4. Make the next field of LAST point to thenew node.
5. Mark the new node as LAST.
6. Make the next field of the new nodepoint to NULL.
46
Write an algorithm to traverse a singly-linked list.
Traversing a Singly-Linked List
Algorithm for traversing a linked list.
2
START
3 5 7
1. Make NEW1 pointto the first node inthe list.
2. Repeat step 3 and 4until NEW1becomes NULL.
3. Display theinformationcontained in thenode marked asNEW1
4. Make NEW1 pointto the next node insequence.
47
Refer to the algorithm to display theelements in the linked list.
102
START
103 105 107
NEW1
Traversing a Singly-Linked List (Contd.)
1. Make NEW1 point tothe first node in thelist.
2. Repeat step 3 and 4until NEW1 becomesNULL.
3. Display the informationcontained in the nodemarked as NEW1
4. Make NEW1 point tothe next node insequence.
48
Refer to the algorithm to display theelements in the linked list.
102
START
103 105 107
NEW1
1. Make NEW1 point tothe first node in thelist.
2. Repeat step 3 and 4until NEW1 becomesNULL.
3. Display the informationcontained in the nodemarked as NEW1
4. Make NEW1 point tothe next node insequence.
Traversing a Singly-Linked List (Contd.)
49
102
START
103 105 107
NEW1
2
1. Make NEW1 point tothe first node in thelist.
2. Repeat step 3 and 4until NEW1 becomesNULL.
3. Display the informationcontained in the nodemarked as NEW1
4. Make NEW1 point tothe next node insequence.
Traversing a Singly-Linked List (Contd.)
50
102
START
103 105 107
2
NEW1
1. Make NEW1 point tothe first node in thelist.
2. Repeat step 3 and 4until NEW1 becomesNULL.
3. Display the informationcontained in the nodemarked as NEW1
4. Make NEW1 point tothe next node insequence.
Traversing a Singly-Linked List (Contd.)
51
102
START
103 105 107
2
NEW1
3
1. Make NEW1 point tothe first node in thelist.
2. Repeat step 3 and 4until NEW1 becomesNULL.
3. Display the informationcontained in the nodemarked as NEW1
4. Make NEW1 point tothe next node insequence.
Traversing a Singly-Linked List (Contd.)
52
102
START
103 105 107
2 3
NEW1
1. Make NEW1 point tothe first node in thelist.
2. Repeat step 3 and 4until NEW1 becomesNULL.
3. Display the informationcontained in the nodemarked as NEW1
4. Make NEW1 point tothe next node insequence.
Traversing a Singly-Linked List (Contd.)
53
102
START
103 105 107
2 3
NEW1
5
1. Make NEW1 point tothe first node in thelist.
2. Repeat step 3 and 4until NEW1 becomesNULL.
3. Display the informationcontained in the nodemarked as NEW1
4. Make NEW1 point tothe next node insequence.
Traversing a Singly-Linked List (Contd.)
54
102
START
103 105 107
2 3 5
NEW1
1. Make NEW1 point tothe first node in thelist.
2. Repeat step 3 and 4until NEW1 becomesNULL.
3. Display the informationcontained in the nodemarked as NEW1
4. Make NEW1 point tothe next node insequence.
Traversing a Singly-Linked List (Contd.)
55
102
START
103 105 107
2 3 5
NEW1
7
1. Make NEW1 point tothe first node in thelist.
2. Repeat step 3 and 4until NEW1 becomesNULL.
3. Display the informationcontained in the nodemarked as NEW1
4. Make NEW1 point tothe next node insequence.
Traversing a Singly-Linked List (Contd.)
56
102
START
103 105 107
2 3 5 7
NEW1 = NULL
Traversal complete
1. Make NEW1 point tothe first node in thelist.
2. Repeat step 3 and 4until NEW1 becomesNULL.
3. Display the informationcontained in the nodemarked as NEW1
4. Make NEW1 point tothe next node insequence.
Traversing a Singly-Linked List (Contd.)
57
TRAVERSING IN LIST
Algorithm traversing()
{
1.new1 = Start
2.while(new1 != NULL)
2.1 Print new1 -> info
2.2 new1 = new1 -> next
}
58
Write an algorithm to insert a node in the beginning of alinked list.
Inserting a Node in a Singly-Linked List (Contd.)
59
START
15 17 20
1. Allocate memory for thenew node.
2. Assign value to the datafield of the new node.
3. Make the next field ofthe new node point tothe first node in the list.
4. Make START, point tothe new node.
Algorithm to insert a node in thebeginning of a linked list
10
Inserting a Node in a Singly-Linked List(Contd.)
60
10
START
10 15 17 20
new1
1. Allocate memory forthe new node.
2. Assign value to thedata field of the newnode.
3. Make the next field ofthe new node point tothe first node in thelist.
4. Make START, point tothe new node.
Insert 7
Inserting a Node in a Singly-Linked List(Contd.)
61
10
START
10 15 20
new1
7
1. Allocate memory forthe new node.
2. Assign value to thedata field of the newnode.
3. Make the next field ofthe new node point tothe first node in thelist.
4. Make START, point tothe new node.
17
Insert 7
Inserting a Node in a Singly-Linked List(Contd.)
62
10
START
10 15 17 20
new1
7
new1 -> next = START
1. Allocate memory forthe new node.
2. Assign value to thedata field of the newnode.
3. Make the next field ofthe new node point tothe first node in thelist.
4. Make START, point tothe new node.
Inserting a Node in a Singly-Linked List(Contd.)
63
1. Allocate memory forthe new node.
2. Assign value to thedata field of the newnode.
3. Make the next field ofthe new node point tothe first node in thelist.
4. Make START, point tothe new node.
START = new1
New1 -> next = START
Insertion complete
10
START
10 15 17 20
new1
7
Inserting a Node in a Singly-Linked List(Contd.)
64
1. Allocate memory forthe new node.
2. Assign value to thedata field of the newnode.
3. Make the next field ofthe new node point tothe first node in thelist.
4. Make START, point tothe new node.
START = new1
New1 -> next = START
Insertion complete
1010 15 17 20
START
7
Inserting a Node in a Singly-Linked List(Contd.)
65
ALGORITHM TO INSERT NODE AT BEGINING
Start=NULL
Algorithm InsertAtBEG()
{
1. Create node [(new1=(struct node*) malloc(sizeof(struct node))]
2. Enter data [new1 -> info = data]
3. If (Start == NULL)
3.1 new1 -> next = NULL
3.2 Last=new1
3.3 Start=new1
else
3.1 new1 -> next=Start
3.2 Start = new1
}
66
Write an algorithm to insert a node at the particular positionin a linked list.
Inserting a Node in a Singly-Linked List (Contd.)
67
1. Allocate memory for the new node.
2. Assign value to the data field of the newnode.
3. Identify the nodes after which the newnode is to be inserted. Mark it asprevious a. Make previous node point to the
first node and set count=1 b. Repeat step c and step d until
count becomes equal to location-1 c. Count=count+1. d. Make previous point to next node
in sequence
4. Make the next field of the new nodepoint to the next of previous node
5. Make the next field of previous point tothe new node.
Insert 16 At LOC = 3
START
5 17 210
Inserting a Node in a Singly-Linked List (Contd.)
68
10
START
10 5 17 2
new1
1.Allocate memory for the new node.
2. Assign value to the data field of the newnode.
3. Identify the nodes after which the newnode is to be inserted. Mark it as previous a. Make previous node point to the first
node and set count=1 b. Repeat step c and step d until count
becomes equal to location-1 c. Count=count+1. d. Make previous point to next node in
sequence
4. Make the next field of the new node pointto the next of previous node
5.Make the next field of previous point to thenew node.
Inserting a Node in a Singly-Linked List (Contd.)
69
10
START
10 5 17 2
Insert 16
LOC = 3
16
new1
1.Allocate memory for the new node.
2. Assign value to the data field of the newnode.
3. Identify the nodes after which the newnode is to be inserted. Mark it as previous a. Make previous node point to the first
node and set count=1 b. Repeat step c and step d until count
becomes equal to location-1 c. Count=count+1. d. Make previous point to next node in
sequence
4. Make the next field of the new node pointto the next of previous node
5.Make the next field of previous point to thenew node.
Inserting a Node in a Singly-Linked List (Contd.)
70
10
START
10 5 17 2
Insert 16
LOC = 3
16
new1
1.Allocate memory for the new node.
2. Assign value to the data field of the newnode.
3. Identify the nodes after which the newnode is to be inserted. Mark it as previous a. Make previous node point to the
first node and set count=1 b. Repeat step c and step d until count
becomes equal to location-1 c. Count=count+1. d. Make previous point to next node
in sequence
4. Make the next field of the new node pointto the next of previous node
5.Make the next field of previous point to thenew node.
Inserting a Node in a Singly-Linked List (Contd.)
71
10
START
10 5 17 2
previous
16
new1
Count=1
1.Allocate memory for the new node.
2. Assign value to the data field of the newnode.
3. Identify the nodes after which the newnode is to be inserted. Mark it asprevious a. Make previous node point to the
first node and set count=1 b. Repeat step c and step d until
count becomes equal to location-1
c. Count=count+1. d. Make previous point to next
node in sequence
4. Make the next field of the new nodepoint to the next of previous node
5.Make the next field of previous point tothe new node.
Inserting a Node in a Singly-Linked List (Contd.)
72
10
START
10 5 17 2
previous
16
new1
Count=1
1.Allocate memory for the new node.
2. Assign value to the data field of thenew node.
3. Identify the nodes after which thenew node is to be inserted. Mark itas previous a. Make previous node point to
the first node and set count=1 b. Repeat step c and step d
until count becomes equal tolocation-1
c. Count=count+1. d. Make previous point to next
node in sequence
4. Make the next field of the newnode point to the next of previousnode
5.Make the next field of previous pointto the new node.
Inserting a Node in a Singly-Linked List (Contd.)
73
10
START
10 5 17 2
previous
16
new1
Count=2
1.Allocate memory for the new node.
2. Assign value to the data field of thenew node.
3. Identify the nodes after which the newnode is to be inserted. Mark it asprevious a. Make previous node point to the
first node and set count=1 b. Repeat step c and step d until
count becomes equal to location-1
c. Count=count+1. d. Make previous point to next
node in sequence
4. Make the next field of the new nodepoint to the next of previous node
5.Make the next field of previous point tothe new node.
Inserting a Node in a Singly-Linked List (Contd.)
74
10
START
10 5 17 2
Nodes located
Insert 16
previous
16
new1
1.Allocate memory for the newnode.
2. Assign value to the data fieldof the new node.
3. Identify the nodes after whichthe new node is to beinserted. Mark it as previous a. Make previous node
point to the first nodeand set count=1
b. Repeat step c and stepd until count becomesequal to location-1
c. Count=count+1. d. Make previous point to
next node in sequence
4. Make the next field of thenew node point to the next ofprevious node
5.Make the next field of previouspoint to the new node.
Inserting a Node in a Singly-Linked List (Contd.)
75
10
START
10 5 17 2
16
new1
new1 -> next = previous->next
previous
1.Allocate memory for the new node.
2. Assign value to the data field of thenew node.
3. Identify the nodes after which the newnode is to be inserted. Mark it asprevious a. Make previous node point to the
first node and set count=1 b. Repeat step c and step d until
count becomes equal to location-1
c. Count=count+1. d. Make previous point to next
node in sequence
4. Make the next field of the new nodepoint to the next of previous node
5.Make the next field of previous point tothe new node.
Inserting a Node in a Singly-Linked List (Contd.)
76
10
START
10 5 17 2
16
new1
previous -> next = new1
new1 -> next = previous->next
previous
1.Allocate memory for the new node.
2. Assign value to the data field ofthe new node.
3. Identify the nodes after whichthe new node is to be inserted.Mark it as previous a. Make previous node point
to the first node and setcount=1
b. Repeat step c and step duntil count becomes equal to location-1
c. Count=count+1. d. Make previous point to
next node in sequence
4. Make the next field of the newnode point to the next of previousnode
5.Make the next field of previouspoint to the new node.
Inserting a Node in a Singly-Linked List (Contd.)
77
10
START
10 5 17 2
16
previous -> next = new1
Insertion complete
previous
new1 -> next = previous->next
1.Allocate memory for the new node.
2. Assign value to the data field ofthe new node.
3. Identify the nodes after which thenew node is to be inserted. Mark itas previous a. Make previous node point
to the first node and setcount=1
b. Repeat step c and step duntil count becomes equal tolocation-1
c. Count=count+1. d. Make previous point to
next node in sequence
4. Make the next field of the newnode point to the next of previousnode
5.Make the next field of previouspoint to the new node.
Inserting a Node in a Singly-Linked List (Contd.)
78
ALGORITHM TO INSERT NODE At PARTICULAR POSITION IN A LINKED LIST
Algorithm InsertAtSpec()
{
1. Create node [(new1=(struct node*) malloc(sizeof(struct node))]
2. Enter Data and Location
3. new1->info=Data
4. If (Location == 1)
4.1 new1 -> next = Start
4.2 Start = new1
Else
4.1 Previous = Start
4.2 Count = 1
4.3 While( Count <= Location - 1 && Previous->next !=NULL)
4.3.1 Previous = Previous -> next
4.3.2 Count++
4.4 new1 -> next = Previous -> next
4.5 Previous -> next = new1
}
79
Write an algorithm to insert a node in a Sorted linked list.
Inserting a Node in a Singly-Linked List (Contd.)
80
10
START
10 15 17 20
Insert 16
Inserting a Node in aSingly-Linked List (Contd.)
1. Allocate memory for the new node.2. Assign value to the data field of the new node.3. If data of newnode is less than the data of start
node, Thena. make newnode point to the
start nodeb. make start point to the
newnode4. Otherwise,Identify the nodes between which the
new node is to be inserted. Mark them asprevious and current. To locate previous andcurrent, execute the following steps:a. Make current point to the first node.b. Make previous point to NULL.c. Repeat step d and step e until current.info
becomes greater than newnode.info orcurrent becomes equal to NULL.
d. Make previous point to current.e. Make current point to the next node in
sequence.5. Make the next field of the new node point to
current.6. Make the next field of previous point to thenew node.
81
10
START
10 15 17 20
new1
1. Allocate memory for the new node.2. Assign value to the data field of the
new node.3. If data of newnode is less than the
data of start node, Thena. make newnode point to the
start nodeb. make start point to the
newnode4. Otherwise,Identify the nodes between
which the new node is to beinserted. Mark them as previousand current. To locate previous andcurrent, execute the following steps:a. Make current point to the first
node.b. Make previous point to NULL.c. Repeat step d and step e until
current.info becomes greaterthan newnode.info or currentbecomes equal to NULL.
d. Make previous point to current.e. Make current point to the next
node in sequence.5. Make the next field of the new node
point to current.6. Make the next field of previous point
to the new node.
Inserting a Node in a Singly-Linked List (Contd.)
82
10
START
10 15 17 20
16
new1
1. Allocate memory for the new node.2. Assign value to the data field of the new
node.3. If data of newnode is less than the data of
start node, Thena. make newnode point to the
start nodeb. make start point to the
newnode4. Otherwise,Identify the nodes between
which the new node is to be inserted.Mark them as previous and current. Tolocate previous and current, execute thefollowing steps:a. Make current point to the first node.b. Make previous point to NULL.c. Repeat step d and step e until
current.info becomes greater thannewnode.info or current becomesequal to NULL.
d. Make previous point to current.e. Make current point to the next node
in sequence.5. Make the next field of the new node point
to current.6. Make the next field of previous point to thenew node.
Inserting a Node in a Singly-Linked List (Contd.)
83
10
START
10 15 17 20
16
new1
1. Allocate memory for the new node.2. Assign value to the data field of the new
node.3. If data of newnode is less than the data
of start node, Thena. make newnode point to the
start nodeb. make start point to the
newnode4. Otherwise,Identify the nodes between
which the new node is to be inserted.Mark them as previous and current. Tolocate previous and current, executethe following steps:a. Make current point to the first
node.b. Make previous point to NULL.c. Repeat step d and step e until
current.info becomes greaterthan newnode.info or currentbecomes equal to NULL.
d. Make previous point to current.e. Make current point to the next
node in sequence.5. Make the next field of the new node point
to current.6. Make the next field of previous point to
thenew node.
Inserting a Node in a Singly-Linked List (Contd.)
84
10
START
10 15 17 20
16
new1
1. Allocate memory for the new node.2. Assign value to the data field of the
new node.3. If data of newnode is less than the
data of start node, Thena. make newnode point to the
start nodeb. make start point to the
newnode4. Otherwise,Identify the nodes
between which the new node is tobe inserted. Mark them as previousand current. To locate previous andcurrent, execute the following steps:a. Make current point to the first
node.b. Make previous point to NULL.c. Repeat step d and step e until
current.info becomes greaterthan newnode.info or currentbecomes equal to NULL.
d. Make previous point to current.e. Make current point to the next
node in sequence.5. Make the next field of the new node
point to current.6. Make the next field of previous point
to the new node.
Inserting a Node in a Singly-Linked List (Contd.)
85
10
START
10 15 17 20
current
16
new1
1. Allocate memory for the new node.2. Assign value to the data field of the
new node.3. If data of newnode is less than the
data of start node, Thena. make newnode point to the
start nodeb. make start point to the
newnode4. Otherwise,Identify the nodes between
which the new node is to beinserted. Mark them as previous andcurrent. To locate previous andcurrent, execute the following steps:a. Make current point to the first
node.b. Make previous point to NULL.c. Repeat step d and step e until
current.info becomes greaterthan newnode.info or currentbecomes equal to NULL.
d. Make previous point to current.e. Make current point to the next
node in sequence.5. Make the next field of the new node
point to current.6. Make the next field of previous point to
the new node.
Inserting a Node in a Singly-Linked List (Contd.)
86
10
START
10 15 17 20
current
previous = NULL
16
new1
1. Allocate memory for the new node.2. Assign value to the data field of the new
node.3. If data of newnode is less than the data
of start node, Thena. make newnode point to the
start nodeb. make start point to the
newnode4. Otherwise,Identify the nodes between
which the new node is to be inserted.Mark them as previous and current. Tolocate previous and current, executethe following steps:a. Make current point to the first
node.b. Make previous point to NULL.c. Repeat step d and step e until
current.info becomes greater thannewnode.info or current becomesequal to NULL.
d. Make previous point to current.e. Make current point to the next
node in sequence.5. Make the next field of the new node point
to current.6. Make the next field of previous point to
the new node.
Inserting a Node in a Singly-Linked List (Contd.)
87
10
START
10 15 17 20
current
previous = NULL
16
new1
1. Allocate memory for the new node.2. Assign value to the data field of the new
node.3. If data of newnode is less than the data of
start node, Thena. make newnode point to the
start nodeb. make start point to the
newnode4. Otherwise,Identify the nodes between
which the new node is to be inserted.Mark them as previous and current. Tolocate previous and current, execute thefollowing steps:a. Make current point to the first node.b. Make previous point to NULL.c. Repeat step d and step e until
current.info becomes greater thannewnode.info or current becomesequal to NULL.
d. Make previous point to current.e. Make current point to the next node
in sequence.5. Make the next field of the new node point
to current.6. Make the next field of previous point to thenew node.
Inserting a Node in a Singly-Linked List (Contd.)
88
10
START
10 15 17 20
currentprevious
16
new1
1. Allocate memory for the new node.2. Assign value to the data field of the
new node.3. If data of newnode is less than the
data of start node, Thena. make newnode point to the
start nodeb. make start point to the
newnode4. Otherwise,Identify the nodes between
which the new node is to beinserted. Mark them as previous andcurrent. To locate previous andcurrent, execute the following steps:a. Make current point to the first
node.b. Make previous point to NULL.c. Repeat step d and step e until
current.info becomes greaterthan newnode.info or currentbecomes equal to NULL.
d. Make previous point to current.e. Make current point to the next
node in sequence.5. Make the next field of the new node
point to current.6. Make the next field of previous point to
the new node.
Inserting a Node in a Singly-Linked List (Contd.)
89
10
START
10 15 17 20
currentprevious
16
new1
1. Allocate memory for the new node.2. Assign value to the data field of the new
node.3. If data of newnode is less than the data
of start node, Thena. make newnode point to the
start nodeb. make start point to the
newnode4. Otherwise,Identify the nodes between
which the new node is to be inserted.Mark them as previous and current. Tolocate previous and current, executethe following steps:a. Make current point to the first
node.b. Make previous point to NULL.c. Repeat step d and step e until
current.info becomes greaterthan newnode.info or currentbecomes equal to NULL.
d. Make previous point to current.e. Make current point to the next
node in sequence.5. Make the next field of the new node
point to current.6. Make the next field of previous point to
the new node.
Inserting a Node in a Singly-Linked List (Contd.)
90
10
START
10 15 17 20
currentprevious
16
new1
1. Allocate memory for the new node.2. Assign value to the data field of the
new node.3. If data of newnode is less than the data
of start node, Thena. make newnode point to the
start nodeb. make start point to the
newnode4. Otherwise,Identify the nodes between
which the new node is to be inserted.Mark them as previous and current.To locate previous and current,execute the following steps:a. Make current point to the first
node.b. Make previous point to NULL.c. Repeat step d and step e until
current.info becomes greaterthan newnode.info or currentbecomes equal to NULL.
d. Make previous point to current.e. Make current point to the next
node in sequence.5. Make the next field of the new node
point to current.6. Make the next field of previous point to
the new node.
Inserting a Node in a Singly-Linked List (Contd.)
91
10
START
10 15 17 20
currentprevious
16
new1
1. Allocate memory for the new node.2. Assign value to the data field of the new
node.3. If data of newnode is less than the data
of start node, Thena. make newnode point to the
start nodeb. make start point to the
newnode4. Otherwise,Identify the nodes between
which the new node is to be inserted.Mark them as previous and current. Tolocate previous and current, executethe following steps:a. Make current point to the first
node.b. Make previous point to NULL.c. Repeat step d and step e until
current.info becomes greaterthan newnode.info or currentbecomes equal to NULL.
d. Make previous point to current.e. Make current point to the next
node in sequence.5. Make the next field of the new node
point to current.6. Make the next field of previous point to
the new node.
Inserting a Node in a Singly-Linked List (Contd.)
92
10
START
10 15 17 20
currentprevious
16
new1
1. Allocate memory for the new node.2. Assign value to the data field of the new
node.3. If data of newnode is less than the data
of start node, Thena. make newnode point to the
start nodeb. make start point to the
newnode4. Otherwise,Identify the nodes between
which the new node is to be inserted.Mark them as previous and current. Tolocate previous and current, executethe following steps:a. Make current point to the first
node.b. Make previous point to NULL.c. Repeat step d and step e until
current.info becomes greater thannewnode.info or current becomesequal to NULL.
d. Make previous point to current.e. Make current point to the next
node in sequence.5. Make the next field of the new node point
to current.6. Make the next field of previous point to
the new node.
Inserting a Node in a Singly-Linked List (Contd.)
93
10
START
10 15 17 20
Nodes located
currentprevious
16
new1
1. Allocate memory for the new node.2. Assign value to the data field of the new
node.3. If data of newnode is less than the data of
start node, Thena. make newnode point to the
start nodeb. make start point to the
newnode4. Otherwise,Identify the nodes between
which the new node is to be inserted.Mark them as previous and current. Tolocate previous and current, execute thefollowing steps:a. Make current point to the first node.b. Make previous point to NULL.c. Repeat step d and step e until
current.info becomes greater thannewnode.info or current becomesequal to NULL.
d. Make previous point to current.e. Make current point to the next node
in sequence.5. Make the next field of the new node point
to current.6. Make the next field of previous point to thenew node.
Inserting a Node in a Singly-Linked List (Contd.)
94
10
START
10 15 17 20
16
new1
new1 -> next = current
currentprevious
1. Allocate memory for the new node.2. Assign value to the data field of the new
node.3. If data of newnode is less than the data
of start node, Thena. make newnode point to the
start nodeb. make start point to the
newnode4. Otherwise,Identify the nodes between
which the new node is to be inserted.Mark them as previous and current. Tolocate previous and current, executethe following steps:a. Make current point to the first
node.b. Make previous point to NULL.c. Repeat step d and step e until
current.info becomes greater thannewnode.info or current becomesequal to NULL.
d. Make previous point to current.e. Make current point to the next
node in sequence.5. Make the next field of the new node
point to current.6. Make the next field of previous point to
the new node.
Inserting a Node in a Singly-Linked List (Contd.)
95
10
START
10 15 17 20
16
new1
previous -> next = new1
new1 -> next = current
Insertion complete
1. Allocate memory for the new node.2. Assign value to the data field of the new
node.3. If data of newnode is less than the data of
start node, Thena. make newnode point to the
start nodeb. make start point to the
newnode4. Otherwise,Identify the nodes between
which the new node is to be inserted.Mark them as previous and current. Tolocate previous and current, execute thefollowing steps:a. Make current point to the first
node.b. Make previous point to NULL.c. Repeat step d and step e until
current.info becomes greater thannewnode.info or current becomesequal to NULL.
d. Make previous point to current.e. Make current point to the next
node in sequence.5. Make the next field of the new node point
to current.6. Make the next field of previous point to
the new node.
currentprevious
Inserting a Node in a Singly-Linked List (Contd.)
96
10
START
10 15 17 20
16
newnode
previous -> next = new1
new1 -> next = current
Insertion complete
1. Allocate memory for the new node.2. Assign value to the data field of the new
node.3. If data of newnode is less than the data
of start node, Thena. make newnode point to the
start nodeb. make start point to the
newnode4. Otherwise,Identify the nodes between
which the new node is to be inserted.Mark them as previous and current.To locate previous and current,execute the following steps:a. Make current point to the first
node.b. Make previous point to NULL.c. Repeat step d and step e until
current.info becomes greaterthan newnode.info or currentbecomes equal to NULL.
d. Make previous point to current.e. Make current point to the next
node in sequence.5. Make the next field of the new node
point to current.6. Make the next field of previous point to
the new node.
currentprevious
Inserting a Node in a Singly-Linked List (Contd.)
97
ALGORITHM TO INSERT NODE IN A SORTED LINKED LIST
Algorithm InsertAtSorted()
{
1. Enter Data
2. Create node [(new1=(struct node*) malloc(sizeof(struct node))]
3. new1->info=Data
4. If (Data <= Start -> info)
4.1 new1 -> next = Start
4.2 Start = new1
Else
4.1 Current = Start
4.2 Previous = NULL
4.3While( Data >= Current -> info && Current != NULL)
4.3.1 Previous = Current
4.3.2 Current = Current -> next
4.4 new1 -> next = Current
4.5 Previous -> next = new1
}
98
Deleting a Node from a Singly-Linked List
Delete operation in a linked list refers to the process ofremoving a specified node from the list.
You can delete a node from the following places in a linkedlist:
Beginning of the list
Between two nodes in the list
End of the list
99
Write an algorithm to delete the first node in a linked list.
Deleting a Node From the Beginning of the List
100
1. Mark the first node in the listas current.
2. Make START point to thenext node in its sequence.
3. Release the memory for thenode marked as current.
START
15 17 20
Algorithm to delete a node from thebeginning of a linked list.
Deleting a Node From the Beginning of the List (Contd.)
10
101
10
START
15 17 20
current = START
10
current
1. Mark the first node in the listas current.
2. Make START point to thenext node in its sequence.
3. Release the memory for thenode marked as current.
Deleting a Node From the Beginning of the List (Contd.)
102
10
START
15 17 20
current = START
10
START = START -> next
current
START
1. Mark the first node in the listas current.
2. Make START point to thenext node in its sequence.
3. Release the memory for thenode marked as current.
Deleting a Node From the Beginning of the List (Contd.)
103
START
15 17 20
Memory released
10
current
Delete operation complete
current = STARTSTART = START -> next
1. Mark the first node in the listas current.
2. Make START point to thenext node in its sequence.
3. Release the memory for thenode marked as current.
Deleting a Node From the Beginning of the List (Contd.)
104
ALGORITHM TO DELETE A NODE FROM THE BEGINNING
Algorithm DeleteAtBeg()
{
1. If (Start == NULL)
1.1 Print "underflow“
else
1.1 Current = Start
1.2 Start = Start -> next
1.3 Current -> next = NULL
1.4 Release the memory [ free (Current) ]
}
105
Write an algorithm to delete the End node in a linked list.
Deleting a Node From the Beginning of the List
106
1. Mark the firstnode in the list ascurrent..
2. Repeat step 3untill currentbecomes Lastnode.
3. Make currentpoint to the nextnode in itssequence.
4. Release thememory for thenode marked asLast.
5. Make Currentpoint to the lastnode
START
15 17 20
Algorithm to delete a node from theEnd.
Deleting a Node From the Beginning
of the List (Contd.)
10
Last
107
10
START
15 17 20
current = START
10
current
Deleting a Node From the Beginning of a Linked List (Contd.)
1. Mark the first node in the listas current..
2. Repeat step 3 untill currentbecomes Last node.
3. Make current point to thenext node in its sequence.
4. Release the memory for thenode marked as Last.
5. Make Current point to thelast node
Last
108
10
START
15 17 2010
current
1. Mark the first node in the listas current..
2. Repeat step 3 untill currentbecomes Last node.
3. Make current point to thenext node in its sequence.
4. Release the memory for thenode marked as Last.
5. Make Current point to thelast node
Last
Deleting a Node From the Beginning of a Linked List (Contd.)
109
10
START
15 17 2010
1. Mark the first node in the listas current..
2. Repeat step 3 untill next ofcurrent becomes Last node.
3. Make current point to thenext node in its sequence.
4. Release the memory for thenode marked as Last.
5. Make Current point to thelast node
Last
current
Deleting a Node From the Beginning of a Linked List (Contd.)
110
10
START
15 17 2010
1. Mark the first node in the listas current..
2. Repeat step 3 untill next ofcurrent becomes Last node.
3. Make current point to thenext node in its sequence.
4. Release the memory for thenode marked as Last.
5. Make Current point to thelast node
Last
current
Deleting a Node From the Beginning of a Linked List (Contd.)
111
10
START
15 17 2010
1. Mark the first node in the listas current..
2. Repeat step 3 untill next ofcurrent becomes Last node.
3. Make current point to thenext node in its sequence.
4. Release the memory for thenode marked as Last.
5. Make Current point to thelast node
Last
current
Deleting a Node From the Beginning of a Linked List (Contd.)
112
10
START
15 17 2010
1. Mark the first node in the listas current..
2. Repeat step 3 untill next ofcurrent becomes Last node.
3. Make current point to thenext node in its sequence.
4. Release the memory for thenode marked as Last.
5. Make Current point to thelast node
Last
current
Delete operation complete
Deleting a Node From the Beginning of a Linked List (Contd.)
113
ALGORITHM TO DELETE A NODE FROM THE END
Algorithm DeleteAtEnd()
{
1. If (Start == NULL)
1.1 Print "underflow“
else If (Start -> next == NULL )
1.1 Release the memory [ free (Start) ]
1.2 Start == NULL
else
1.1 Current = Start
1.2 while ( Current -> next != Last )
1.2.1 Current = Current -> next
1.3 Current -> next = NULL
1.4 Release the memory [ free (Last) ]
1.5 Last = Current
}
114
Write an algorithm to delete a node from a specific positionin a linked list.
Deleting a Node Between two Nodes in the List
115
Algorithm to delete a node from aspecific position.
1. Locate the node to be deleted.Mark the node to be deleted ascurrent and its predecessor asprevious. To locate current andprevious, execute the followingsteps:
a. Set previous = NULLb. Set current = STARTc. Repeat step d and e
until either the nodeis found or currentbecomes NULL.
d. Make previous pointto current .
e. Make current pointto the next node insequence.
2. Make the next field of previouspoint to the successor ofcurrent.
3. Release the memory for thenode marked as current.
Delete 17
START
15 17 2010
116
1. Locate the node to be deleted. Mark thenode to be deleted as current and itspredecessor as previous. To locatecurrent and previous, execute thefollowing steps:
a. Set previous = NULLb. Set current = START c. Repeat step d and e until
either the node is found orcurrent becomes NULL.
d. Make previous point tocurrent.
e. Make current point to thenext node in sequence.
2. Make the next field of previous point tothe successor of current.
3. Release the memory for the nodemarked as current.
Delete 17
10
START
10 15 17 20
Deleting a Node Between two Nodes in the List (Contd.)
117
10
START
10 15 17 20
1. Locate the node to be deleted. Mark thenode to be deleted as current and itspredecessor as previous. To locatecurrent and previous, execute thefollowing steps:
a. Set previous = NULLb. Set current = START c. Repeat step d and e until
either the node is found orcurrent becomes NULL.
d. Make previous point tocurrent.
e. Make current point to thenext node in sequence.
2. Make the next field of previous point tothe successor of current.
3. Release the memory for the nodemarked as current.
Delete 17
Previous = NULL
Deleting a Node Between two Nodes in the List (Contd.)
118
10
START
10 15 17 20
Previous = NULL
current
1. Locate the node to be deleted. Mark thenode to be deleted as current and itspredecessor as previous. To locatecurrent and previous, execute thefollowing steps:
a. Set previous = NULLb. Set current = START c. Repeat step d and e until
either the node is found orcurrent becomes NULL.
d. Make previous point tocurrent.
e. Make current point to thenext node in sequence.
2. Make the next field of previous point tothe successor of current.
3. Release the memory for the nodemarked as current.
Delete 17
Deleting a Node Between two Nodes in the List (Contd.)
119
10
START
10 15 17 20
current
1. Locate the node to be deleted. Mark thenode to be deleted as current and itspredecessor as previous. To locatecurrent and previous, execute thefollowing steps:
a. Set previous = NULLb. Set current = START c. Repeat step d and e until
either the node is found orcurrent becomes NULL.
d. Make previous point tocurrent.
e. Make current point to thenext node in sequence.
2. Make the next field of previous point tothe successor of current.
3. Release the memory for the nodemarked as current.
Delete 17
Previous = NULL
Deleting a Node Between two Nodes in the List (Contd.)
120
10
START
10 15 17 20
current
1. Locate the node to be deleted. Mark thenode to be deleted as current and itspredecessor as previous. To locatecurrent and previous, execute thefollowing steps:
a. Set previous = NULLb. Set current = START c. Repeat step d and e until
either the node is found orcurrent becomes NULL.
d. Make previous point tocurrent.
e. Make current point to thenext node in sequence.
2. Make the next field of previous point tothe successor of current.
3. Release the memory for the nodemarked as current.
Delete 17
previous
Deleting a Node Between two Nodes in the List (Contd.)
121
10
START
10 15 17 20
currentcurrent
1. Locate the node to be deleted. Mark thenode to be deleted as current and itspredecessor as previous. To locatecurrent and previous, execute thefollowing steps:
a. Set previous = NULLb. Set current = START c. Repeat step d and e until
either the node is found orcurrent becomes NULL.
d. Make previous point tocurrent.
e. Make current point to thenext node in sequence.
2. Make the next field of previous point tothe successor of current.
3. Release the memory for the nodemarked as current.
Delete 17
previous
Deleting a Node Between two Nodes in the List (Contd.)
122
10
START
10 15 17 20
current
1. Locate the node to be deleted. Mark thenode to be deleted as current and itspredecessor as previous. To locatecurrent and previous, execute thefollowing steps:
a. Set previous = NULLb. Set current = START c. Repeat step d and e until
either the node is found orcurrent becomes NULL.
d. Make previous point tocurrent.
e. Make current point to thenext node in sequence.
2. Make the next field of previous point tothe successor of current.
3. Release the memory for the nodemarked as current.
Delete 17
previous
Deleting a Node Between two Nodes in the List (Contd.)
123
10
START
10 15 17 20
previous current
1. Locate the node to be deleted. Mark thenode to be deleted as current and itspredecessor as previous. To locatecurrent and previous, execute thefollowing steps:
a. Set previous = NULLb. Set current = START c. Repeat step d and e until
either the node is found orcurrent becomes NULL.
d. Make previous point tocurrent.
e. Make current point to thenext node in sequence.
2. Make the next field of previous point tothe successor of current.
3. Release the memory for the nodemarked as current.
Delete 17
previous
Deleting a Node Between two Nodes in the List (Contd.)
124
1. Locate the node to be deleted. Mark thenode to be deleted as current and itspredecessor as previous. To locatecurrent and previous, execute thefollowing steps:
a. Set previous = NULLb. Set current = START c. Repeat step d and e until
either the node is found orcurrent becomes NULL.
d. Make previous point tocurrent.
e. Make current point to thenext node in sequence.
2. Make the next field of previous point tothe successor of current.
3. Release the memory for the nodemarked as current.
Delete 17
10
START
10 15 17 20
current currentprevious
Deleting a Node Between two Nodes in the List (Contd.)
125
1. Locate the node to be deleted. Mark thenode to be deleted as current and itspredecessor as previous. To locatecurrent and previous, execute thefollowing steps:
a. Set previous = NULLb. Set current = START c. Repeat step d and e until
either the node is found orcurrent becomes NULL.
d. Make previous point tocurrent.
e. Make current point to thenext node in sequence.
2. Make the next field of previous point tothe successor of current.
3. Release the memory for the nodemarked as current.
Delete 17
10
START
10 15 17 20
currentprevious
Deleting a Node Between two Nodes in the List (Contd.)
126
Previous -> next = current -> next
1. Locate the node to be deleted. Mark thenode to be deleted as current and itspredecessor as previous. To locatecurrent and previous, execute thefollowing steps:
a. Set previous = NULLb. Set current = START c. Repeat step d and e until
either the node is found orcurrent becomes NULL.
d. Make previous point tocurrent.
e. Make current point to thenext node in sequence.
2. Make the next field of previous point tothe successor of current.
3. Release the memory for the nodemarked as current.
Delete 17
10
START
10 15 17 20
currentprevious
Deleting a Node Between two Nodes in the List (Contd.)
127
Delete operation complete
1. Locate the node to be deleted. Mark thenode to be deleted as current and itspredecessor as previous. To locatecurrent and previous, execute thefollowing steps:
a. Set previous = NULLb. Set current = START c. Repeat step d and e until
either the node is found orcurrent becomes NULL.
d. Make previous point tocurrent.
e. Make current point to thenext node in sequence.
2. Make the next field of previous point tothe successor of current.
3. Release the memory for the nodemarked as current.
Delete 17
10
START
10 15 17 20
current
Previous -> next = current -> next
previous
Deleting a Node Between two Nodes in the List (Contd.)
128
ALGORITHM TO DELETE A NODE FROM THE SPECIFIC POSITION
Algorithm DeleteAtSpec()
{
1. Enter the Location
2. Current = Start
3. Previous = NULL
4. If (Start == 0)
4.1 Print "underflow“
else If ( Location == 1)
4.1 Start = Start -> next
4.2 Current -> next = NULL
4.3 Release the memory [ free (Current) ]
else
4.1 for (i=1 to Location-1)
4.1.1 Previous = Current
4.1.2 Current = Current -> next
4.2 Previous -> next = Current -> next
4.3 Current -> next = NULL
4.4 Release the memory [ free (Current) ]
}
129
Problem StatementDiscuss the advantages and disadvantages of linked lists .
Group Discussion
130
Problem StatementDiscuss the differences between arrays and linked lists .
Group Discussion (Contd.)
131
Linked lists allow _________ access to elements.
Just a minute
Answer:sequential