28. Implement strStr()

题目

Implement strStr().

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

题意

实现字符串匹配，这里我用的时两重循环解决，当然有更好的算法，如KMP

Python实现

class Solution(object):
    def strStr(self, haystack, needle):
        """
        :type haystack: str
        :type needle: str
        :rtype: int
        """
        len1=len(haystack)
        len2=len(needle)
        if len2==0 :return 0
        if len1==0 :return -1
        for i in range(len1):
            k=0
            while k+i<len1 and k<len2 and haystack[k+i]==needle[k]:k+=1
            if k==len2:return i
            if k+i==len1:return -1
            i+=1
        return -1