Implement_strStr().md

028. Implement strStr()

Implement strStr().

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

Method:

class Solution(object):
    def strStr(self, haystack, needle):
        """
        :type haystack: str
        :type needle: str
        :rtype: int
        """
        if not needle:
            return 0
        for i in range(len(haystack)-len(needle)+1):
            if haystack[i:i+len(needle)]==needle:
                return i
        return -1