Implement strStr().py

# https://leetcode.com/problems/implement-strstr/
# Hak Soo Kim
# 2/28/2021

class Solution(object):
    def strStr(self, haystack, needle):
        for i in range(len(haystack) - len(needle) + 1):
            if haystack[i:i + len(needle)] == needle:
                return i
        return -1

        """
        :type haystack: str
        :type needle: str
        :rtype: int
        """

# Implement strStr().
#
# 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().
#
# Example 1:
#
# Input: haystack = "hello", needle = "ll"
# Output: 2
# Example 2:
#
# Input: haystack = "aaaaa", needle = "bba"
# Output: -1
# Example 3:
#
# Input: haystack = "", needle = ""
# Output: 0
#
# Constraints:
#
# 0 <= haystack.length, needle.length <= 5 * 104
# haystack and needle consist of only lower-case English characters.