Find the Index of the First Occurrence in a String

Easy

Given two strings s (haystack) and t (needle), return the index of the first occurrence of t in s, or -1 if not present.

Example 1

Input:  s = "sadbutsad", t = "sad"
Output: 0

Example 2

Input:  s = "leetcode", t = "leeto"
Output: -1

Constraints

• 1 <= s.length, t.length <= 10^4
• Both consist of lowercase English letters.