LeetCode28

LeetCode28：https://leetcode-cn.com/problems/implement-strstr/submissions/

解题思路：滑动窗法

class Solution:
    def strStr(self, haystack: str, needle: str) -> int:
        len1 = len(haystack)
        len2 = len(needle) 
        for i in range(len1-len2+1):
            if haystack[i:i+len2] == needle:
                return i
        return -1