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Solution: Find the Index of the First Occurrence in a String

Explore how to apply the sliding window technique to locate the first occurrence of a substring inside a larger string. Understand the step-by-step approach of sliding a window across the string and comparing substrings to solve this common interview problem efficiently with Python.

Statement

Given two strings haystack and needle, return the index of the first occurrence of needle within haystack. If needle does not exist as a substring of haystack, return 1-1.

Constraints:

  • 11 \leq haystack.length, needle.length 104\leq 10^4

  • haystack and needle consist of only lowercase English characters

Solution

The key intuition behind this solution is to use a fixed-size sliding window of length equal to ...