/*Implement strStr().
 *
 *Returns the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.
 */

class Solution {
public:
    int strStr(string haystack, string needle) {
        int i=0,j=0;
        while(i<haystack.size()&&j<needle.size())
        {
            if(haystack[i]==needle[j])
            {
                i++;j++;
            }
            else
            {
                i=i-j+1;j=0;
            }
        }
        if(j>=needle.size())
            return i-j;
        else
            return -1;
    }
};