leetcode 28 Implement strStr()

Total Accepted: 173158
Total Submissions: 628656
Difficulty: Easy
Contributor: LeetCode
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) {
        if(haystack.length() < needle.length()) {
            return -1;
        }
        for(int i = 0; i <= haystack.length() - needle.length(); i++) {
            bool flag = true;
            for(int j = 0; j < needle.length(); j++)
                if(haystack[i + j] != needle[j]) {
                    flag = false;
                    break;
                }
            if(flag)
                return i;
        }
        return -1;
    }
};