【leetcode刷题笔记】Implement strStr()

Implement strStr().

Returns a pointer to the first occurrence of needle in haystack, or null if needle is not part of haystack.

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暴力法，从haystack第一个字符开始查找needle。

代码如下：

 1 public class Solution {

 2     public String strStr(String haystack, String needle) {

 3         if(haystack == null)

 4             return null;

 5         

 6         if(needle.length() == 0)

 7             return haystack;

 8         

 9         int i,j = 0;

10         for(i = 0;i < haystack.length() - needle.length() + 1;i++){

11             for(j = 0;j < needle.length();j++){

12                 if(haystack.charAt(i+j) != needle.charAt(j))

13                     break;

14             }

15             if(j == needle.length())

16                 return haystack.substring(i,haystack.length());

17         }

18         return null;

19     }

20 }