[LeetCode]28. Implement strStr()

题目：Implement strStr().
Returns the index of the first occurrence of needle in haystack,
or -1 if needle is not part of haystack.

意思是：从haystack字符串中查找给定字符串needle第一次出现的位置

代码如下：

class Solution {public:int strStr(string haystack, string needle) {int m = haystack.length(), n = needle.length();if (!n) return 0;for (int i = 0; i < m - n + 1; i++) {int j = 0;for (; j < n; j++)if (haystack[i + j] != needle[j])break;if (j == n) return i;}return -1;}};