【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：

 public class Solution {
     public String strStr(String haystack, String needle) {
         if(haystack == null)
             return null;

         if(needle.length() == 0)
             return haystack;

         int i,j = 0;
         for(i = 0;i < haystack.length() - needle.length() + 1;i++){
             for(j = 0;j < needle.length();j++){
                 if(haystack.charAt(i+j) != needle.charAt(j))
                     break;
             }
             if(j == needle.length())
                 return haystack.substring(i,haystack.length());
         }
         return null;
     }
 }