To copy the contents of an array A to contents of Array B without using loops and any standard string copy functions.

#include<stdio.h>
int Copy_Array(int A[],int B[], int n,int i)
{
    if(i==n)
        return 0;
    B[i]=A[i];
    Copy_Array(A,B,n,i+1);
return 0;
}

int main()
{
    int A[10],B[10],i,n;
    printf("Enter size : ");
    scanf("%d",&n);
    printf("Enter Array : ");
    for(i=0;i<n;i++)
        scanf("%d",&A[i]);
    printf("\nArray A : ");
    for(i=0;i<n;i++)
        printf("%d ",A[i]);
    Copy_Array(A,B,n,0);
    printf("\nArray B : ");
    for(i=0;i<n;i++)
        printf("%d ",B[i]);
return 0;
}

Let me know your thoughts.

WAP to return all anagrams from the array of strings. (all possible permutation of a String)

#include<stdio.h>
#include<string.h>
int anagram(char S[10],int l,char C[10])
{
    char D[10];
    int j,k,m=strlen(C),i;
    for(j=0;j<=m;j++)
    {
        for(k=m;k>j;k--)
            D[k]=C[k-1];
        D[k]=S[m];
        D[m+1]=NULL;
        for(k=j-1;k>=0;k--)
            D[k]=C[k];
        if((m+1)==l)
            printf("%s\n",D);
        else
            anagram(S,l,D);
    }
return 0;

}
int main()
{
    char S[10],C[10];
    C[0]=NULL;
    gets(S);
    printf("\n");
    anagram(S,strlen(S),C);
return 0;
}

The character 'a' to 'z' are encoded as 1 - 26. Given a string of digits, compute the number of valid decodings of the string. For example, both 'aa' and 'k' can be encoded as '11'. Hence num_valid_encodings('11') = 2.

      recursive 

#include <stdio.h>
#include <string.h>
int count_decode(char S[10],int n)
{
    int x1=S[n-1]-'0',x2=S[n-2]-'0',z;
    if(!n)
        return 0;
    else if(n==1)
    {
        return 1;
    }
    else
    {
        z=x2*10+x1;
      //  printf("z=%d ",z);
        if(z>26)
            return (count_decode(S,n-1));
        else if(n==2)
            return (count_decode(S,n-1) + count_decode(S,n-2)+1);
        else
            return (count_decode(S,n-1) + count_decode(S,n-2));
    }
}
int main()
{
    int i,j,n;
    char S[10];
    gets(S);
    n=strlen(S);
    printf("< %d >",count_decode(S,n));
return 0;
}