[Leetcode][Python]28: Implement strStr()

# -*- coding: utf8 -*-‘‘‘__author__ = ‘[email protected]‘

28: Implement strStr()https://oj.leetcode.com/problems/implement-strstr/

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

===Comments by Dabay===在长字符串中找子串，当然是KMP算法。既然是三人研究出来的算法，肯定不简单。空了再来研究研究吧。这里给的是直观的解法，遍历长字符串的时候，开始和短字符串一个一个字符进行比较，如果都比较完了，说明找到了。如果遍历完了，还没有返回的话，说明没有找到，返回-1。‘‘‘

class Solution:    # @param haystack, a string    # @param needle, a string    # @return an integer    def strStr(self, haystack, needle):        i = 0        while i < len(haystack) - len(needle) + 1:            m,n = i,0            while n < len(needle) and haystack[m] == needle[n]:                m += 1                n += 1            if n == len(needle):                return i            i += 1        else:            return -1

def main():    sol = Solution()    haystack = "ahi"    needle = "hi"    print sol.strStr(haystack, needle)

if __name__ == "__main__":    import time    start = time.clock()    main()    print "%s sec" % (time.clock() - start)