LeetCode题解之 Implement strStr()

1、题目描述

2.题目分析

字符串操作，注意边界条件即可。

3.代码

 int strStr(string haystack, string needle) {
        int n = needle.size();
        int res = -1;
        if( needle.size() == 0)
            return 0;
        for(string::iterator it = haystack.begin() ; it != haystack.end(); ++it){
            if((*it) == needle[0]){
                bool isEqual = true;
                bool isEnd = false;
                for(int i = 0 ; i < n; i++){
                    if( it + i == haystack.end() ){
                        isEnd = true;
                        break;
                    }
                    if( needle[i] != *(it+i)){
                        isEqual = false;
                        break;
                    }
                }
                if( isEnd == true )
                    break;
                if( isEqual == true){
                    res = it-haystack.begin();
                    break;
                }
                
            }
        }
        return res;
        
    }