leetcode 28

28. Implement strStr()

    def strStr(self, haystack, needle):
        """
        :type haystack: str
        :type needle: str
        :rtype: int
        """
        h = len(haystack)
        n = len(needle)
        for i in range(h - n + 1):
            if haystack[i:i + n] == needle:
                return i
        return -1

返回needle字符串在haystack字符串出现的第一个位置