leetcode--Implement strStr()

Implement strStr().

Returns the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.

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1. public class Solution {  
2.     public int strStr(String haystack, String needle) {  
3.         if(haystack.length()==0 && needle.length()==0) return 0;  
4.         if(haystack.length()==0) return -1;  
5.         if(haystack.length()<needle.length()) return -1;  
6.         for(int i=0;i<haystack.length();i++){  
7.             int j = 0;  
8.             while(j<needle.length()){  
9.                 if(i+j >= haystack.length()) return -1;  
10.                 if(haystack.charAt(i+j)==needle.charAt(j)){  
11.                     j++;  
12.                 }else{  
13.                     break;  
14.                 }  
15.             }  
16.             if(j==needle.length()){  
17.                 return i;  
18.             }  
19.         }  
20.         return -1;  
21.     }  
22. }  

原文链接http://blog.youkuaiyun.com/crazy__chen/article/details/45603507