【Leetcode Algorithm】Implement strStr()

Implement strStr().

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

自己的代码：

public class Solution {    public int strStr(String haystack, String needle) {        for(int i=0;i<=haystack.length()-needle.length();i++){            boolean flag = true;            for(int j=0;j<needle.length();j++){                //只要有一个字符不匹配，则匹配失败                if(haystack.charAt(i+j)!=needle.charAt(j)){                    flag = false;                    break;                   }            }            //若经过比较之后，flag==true，则匹配成功，返回i            if(flag==true){                return i;            }        }        return -1;    }}