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Rahul Kumar Barnwal @rahulgithub-web

Top Interview 150: Find First Occurrence Of A Substring In A String

Find first occurrence of substring in string efficiently using built-in indexOf() or manual sliding window approach with O(n-m+1)*m time complexity.

Top Interview 150
The problem asks us to find the first occurrence of a substring (needle) in a string (haystack) efficiently. Let’s break it down Find the Index of the First Occurrence in a String and solve it using multiple approaches, including a manual implementation.


🚀 Problem Description
Given two strings needle and haystack:

Return the index of the first occurrence of needle in haystack.
Return -1 if needle does not exist in haystack.


💡 Examples
Example 1

Input: haystack = "sadbutsad", needle = "sad"  
Output: 0  
Explanation: "sad" appears first at index 0....