38
public static int Tong(int n) { if(n==0) return n; else return (n+Tong(n-1)); } public static int Tong(int n) { int s=0; for(int i=0;i<=n;i++) s=s+i; return s; } public static int Giaithua(int n) { if(n==0||n==1) return 1; else return n*Giaithua(n-1); } public static int Giaithua(int n) { int gt=1; for(int i=2;i<=n;i++) gt=gt*i; return gt; } public static int Mu(int a,int n)
