LeetCode 1624 | Largest Substring Between Two Equal Characters | Python First-Index Trick | AlgoYogi

Welcome to AlgoYogi! 🚀 Start Your Smart Coding Prep at 👉 https://algoyogi.io We solve LeetCode 1624: Largest Substring Between Two Equal Characters using Python and a simple first-index map. Goal: find the maximum length of a substring that lies strictly between two equal characters in s. If no such pair exists, return minus one. Approach: - Scan the string once while storing the first index seen for each character. - When you see the same character again at index j, compute length as j minus first_index minus 1. - Track the maximum over all repeats and return it. If nothing repeats, answer is minus one. 👉 Problem Link: https://leetcode.com/problems/largest-substring-between-two-equal-characters/description/ --- ### ⏱ Timestamps 0:00 Introduction 0:20 Problem Statement 1:00 First-Index Mapping Approach 9:00 Python Code Walkthrough 12:00 Time and Space Complexity --- ### 💡 Why Watch? - Clean O(n) one-pass solution with O(1) space for fixed alphabet - Handles all repeats efficiently without nested loops - Interview friendly and easy to reason about #LeetCode #LargestSubstringBetweenEqualChars #Python #AlgoYogi #HashMap #Strings