【Leetcode】028-Implement strStr()

Question

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:
    def strStr(self, haystack, needle):
        """
        :type haystack: str
        :type needle: str
        :rtype: int
        """
        if len(needle)==0 :
            return 0
        elif needle in haystack:
            # return haystack.find(needle)
            return haystack.index(needle)
        else:
            return -1