Implement strStr().

Given two strings needle and haystack, return theindex of the first occurrence of needle in haystack,or -1 if needle is not partof 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 0when needle is an empty string. This is consistent toC's strstr() and Java's indexOf().

Example 1:

Input: haystack = "hello", needle = "ll"Output: 2

Example 2:

Input: haystack = "aaaaa", needle = "bba"Output: -1

Constraints:

• 1 <= haystack.length, needle.length <=10⁴
• haystack and needle consist of only lowercaseEnglish characters.

class Solution:
def strStr(self, haystack: str, needle: str) ->int:

Implementation in Python3