【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;
    }
}