[Leetcode] 28. Implement strStr()

Problem:

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

Idea: Use two points to go through these two string individually.

Solution:

class Solution(object): def strStr(self, haystack, needle): i=j=0 lenhaystack = len(haystack) lenneedle = len(needle) if lenneedle == 0: return 0 while j!= lenhaystack: if haystack[j] == needle[i]: if i+1 == lenneedle: return j-i else: i += 1 j += 1 elif i != 0: j = j-i+1 i = 0 else: j += 1 return -1