mycode   77.15%

class Solution(object):
def strStr(self, haystack, needle):
"""
:type haystack: str
:type needle: str
:rtype: int
"""
len_1 , len_2 = len(haystack) , len(needle)
for i in range(len_1 - len_2 + 1):
if haystack[i:i+len_2] == needle:
return i
return -1

参考：

要习惯python的.find操作呀

Clarification:

What should we return when needle is an empty string? This is a great question to ask during an interview.

For the purpose of this problem, we will return 0 when needle is an empty string. This is consistent to C's strstr() and Java's indexOf().

class Solution(object):
def strStr(self, haystack, needle):
if not needle:
return 0
return haystack.find(needle)