28. Find the Index of the First Occurrence in a String

LeetCode problem

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.

Example 1:

Input: haystack = “sadbutsad”, needle = “sad” Output: 0 Explanation: “sad” occurs at index 0 and 6. The first occurrence is at index 0, so we return 0.

Example 2:

Input: haystack = “leetcode”, needle = “leeto” Output: -1 Explanation: “leeto” did not occur in “leetcode”, so we return -1.

Code

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

class Solution:
    def strStr(self, haystack: str, needle: str) -> int:
        start = 0
        end = len(needle)

        while end <= len(haystack):
            if haystack[start:end] == needle:
                return start
            start += 1
            end += 1

        return -1