KMP

void getnext(char *s,int *next)
{
    int j , k ;
    next[0] = -1 ;
    j = 0 ; k = -1 ;
    while(j < strlen(s)-1)
    {
        if(k == -1 || s[j] == s[k])
        {
            j++;
            k++;
            next[j] = k ;
        }
        else
            k = next[k] ;
    }
}

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define l 10000000
char str1[l] , str2[l] ;
int next[l] ;
void getnext(char *s,int *next)
{
    int j , k ;
    next[0] = -1 ;
    j = 0 ; k = -1 ;
    while(j < strlen(s)-1)
    {
        if(k == -1 || s[j] == s[k])
        {
            j++;
            k++;
            next[j] = k ;
        }
        else
            k = next[k] ;
    }
}
int main()
{
    int i , j , p ;
    while(scanf("%s%s", str1, str2)!=EOF)
    {
        i = 0 ; j = 0 ; p = 1 ;
		getnext(str2,next);
        while(str1[i]!='\0' && str2[j] !='\0')
        {
            if(str1[i]==str2[j])
            {
                i++; j++;
            }
            else
            {
                if(next[j]==-1)
                {
                    j = 0 ;
                    i++;
                    p = i + 1 ;
                }
                else
                {
                    j = next[j] ;
                    p = p - j ;
                }
            }
        }
        if(str2[j]=='\0')
            printf("%d\n", p);
        else
            printf("NO\n");
    }
}