leetcode 28 - implement strStr().py

"""
Implement strStr().

Given two strings needle and haystack, return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.

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().

Question: https://leetcode.com/problems/implement-strstr/

"""

class Solution:
        def strStr(self, haystack: str, needle: str) -> int:
            if not needle:
                return 0
            
            for i in range(len(haystack)):
                if haystack[i:i+len(needle)] == needle:
                    return i
            return -1