find-the-index-of-the-first-occurrence-in-a-string

Find the Index of the First Occurrence in a String

https://leetcode.com/problems/find-the-index-of-the-first-occurrence-in-a-string/description/

Problem Description

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.

Constraints

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