Implement strStr().
Return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.
Example 1:
Input: haystack = "hello", needle = "ll" Output: 2
Example 2:
Input: haystack = "aaaaa", needle = "bba" Output: -1
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): """ :type haystack: str :type needle: str :rtype: int """ if not needle: return 0 if not haystack: return -1 len_haystack, len_needle = len(haystack), len(needle) for i in range(0, len_haystack - len_needle + 1): cur = haystack[i] if cur == needle[0]: j = 0 while j < len_needle: if haystack[i + j] != needle[j]: break j += 1 if j == len_needle: return i return -1
原文：https://www.cnblogs.com/xuanlu/p/11829275.html