[leetcode] 28. implement strstr()

Implement strStr().

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

class Solution(object):
    def strStr(self, haystack, needle):
        """
        :type haystack: str
        :type needle: str
        :rtype: int
        """
        if not haystack and needle or len(haystack)<len(needle):
            return -1
        if not haystack :
            return 0
        if haystack and not needle:
            return 0
        for i,v in enumerate(haystack):
            if haystack[i:len(needle)+i]==needle:
                return i
            if i==len(haystack)-1:
                return -1

Status: Accepted
Runtime: 848 ms
Ranking: beats 0.30%

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
        if len(haystack)<len(needle):
            return -1
        i=0
        while 1:
            if i+len(needle)>len(haystack):
                return -1
            if haystack[i:i+len(needle)]==needle:
                return i
            i+=1                

Status: Accepted
Runtime: 64 ms
Ranking: beats 43.29%