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