LeetCode 3740 | Minimum Distance Between Three Equal Elements I | Java | Easy | CodeByTushu
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In today’s video, we solve LeetCode 3740 — Minimum Distance Between Three Equal Elements I using Hash Table and Math in Java.
We are given an integer array nums and need to find the minimum distance among all triplets of distinct indices i, j, and k where all three elements have the same value. The distance is calculated as the sum of the absolute differences between each pair of indices. If no value appears at least three times, we return -1.
For sorted indices i less than j and j less than k, the distance simplifies to 2 * (k - i). This means the middle index does not affect the final distance. To find the minimum distance, we only need to check consecutive groups of three occurrences for each value.
We use a Hash Map to store the indices of each element while traversing the array. By checking consecutive triplets, we can find the minimum distance in O(n) time with O(n) auxiliary space.
🔥 Problem Highlights
✅ Mathematical Simplification: Reduces the distance formula to 2 * (k - i)
✅ Middle Index Elimination: Shows why the middle index has no effect on the total distance
✅ Consecutive Triplet Check: Checks consecutive groups of three occurrences to find the minimum span
✅ Hash Map Optimization: Stores element positions efficiently while traversing the array
✅ Optimal Time Complexity: Solves the problem in O(n) time using a single pass
✅ Space Efficiency: Uses O(n) auxiliary space to track element occurrences
⏱️ TIMESTAMPS
00:00 Intro & Daily Challenge Kickoff (Streak 98 Days)
01:44 Problem Understanding & Distance Definition
03:34 Mathematical Simplification: 2 * (k - i)
05:39 Optimal Frequency Map & Adjacent Triplet Scan
07:12 Clean Java Solution Walkthrough Line by Line
08:26 Test Cases Dry Run & Benchmark Verification (1 ms, Beats 100%)
09:38 Time Complexity Analysis (O(N) Linear Time)
10:38 Space Complexity Analysis (O(N) Auxiliary Space)
11:24 Day 10 Wrap-up & Channel Resources
📂 Problem Folder & Detailed Documentation:
https://github.com/CodeByTushu/CodeByTushu-LeetCode-Solutions/tree/main/solutions/April/10-April/3740-Minimum-Distance-Between-Three-Equal-Elements-I
☕ Java Solution:
https://github.com/CodeByTushu/CodeByTushu-LeetCode-Solutions/blob/main/solutions/April/10-April/3740-Minimum-Distance-Between-Three-Equal-Elements-I/Solution.java
🐍 Python Solution:
https://github.com/CodeByTushu/CodeByTushu-LeetCode-Solutions/blob/main/solutions/April/10-April/3740-Minimum-Distance-Between-Three-Equal-Elements-I/solution.py
⚡ C++ Solution:
https://github.com/CodeByTushu/CodeByTushu-LeetCode-Solutions/blob/main/solutions/April/10-April/3740-Minimum-Distance-Between-Three-Equal-Elements-I/solution.cpp
🌐 JavaScript Solution:
https://github.com/CodeByTushu/CodeByTushu-LeetCode-Solutions/blob/main/solutions/April/10-April/3740-Minimum-Distance-Between-Three-Equal-Elements-I/solution.js
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💬 Question of the Day
Why does the intermediate index j cancel out of the distance formula for sorted indices i, j, and k?
1️⃣ Because (j - i) + (k - j) equals (k - i), making the total distance exactly 2 * (k - i)
2️⃣ Because j is always the arithmetic mean of i and k
3️⃣ Because the absolute value function ignores the middle term in all triplets
4️⃣ Because only the first and last elements in an array can be equal
#LeetCode3740 #LeetCode #MinimumDistanceBetweenThreeEqualElementsI #Java #JavaDSA #HashTable #Math #Array #DSA #CodingInterview #ProblemSolving #LeetCodeEasy #DailyLeetCode #JavaProgramming #CodeByTushu
👇 Comment the answer below! 🔥 Close description
In today’s video, we solve LeetCode 3740 — Minimum Distance Between Three Equal Elements I using Hash Table and Math in Java.
We are given an integer array nums and need to find the minimum distance among all triplets of distinct indices i, j, and k where all three elements have the same value. The distance is calculated as the sum of the absolute differences between each pair of indices. If no value appears at least three times, we return -1.
For sorted indices i less than j and j less than k, the distance simplifies to 2 * (k - i). This means the middle index does not affect the final distance. To find the minimum distance, we only need to check consecutive groups of three occurrences for each value.
We use a Hash Map to store the indices of each element while traversing the array. By checking consecutive triplets, we can find the minimum distance in O(n) time with O(n) auxiliary space.
🔥 Problem Highlights
✅ Mathematical Simplification: Reduces the distance formula to 2 * (k - i)
✅ Middle Index Elimination: Shows why the middle index has no effect on the total distance
✅ Consecutive Triplet Check: Checks consecutive groups of three occurrences to find the minimum span
✅ Hash Map Optimization: Stores element positions efficiently while traversing the array
✅ Optimal Time Complexity: Solves the problem in O(n) time using a single pass
✅ Space Efficiency: Uses O(n) auxiliary space to track element occurrences
⏱️ TIMESTAMPS
00:00 Intro & Daily Challenge Kickoff (Streak 98 Days)
01:44 Problem Understanding & Distance Definition
03:34 Mathematical Simplification: 2 * (k - i)
05:39 Optimal Frequency Map & Adjacent Triplet Scan
07:12 Clean Java Solution Walkthrough Line by Line
08:26 Test Cases Dry Run & Benchmark Verification (1 ms, Beats 100%)
09:38 Time Complexity Analysis (O(N) Linear Time)
10:38 Space Complexity Analysis (O(N) Auxiliary Space)
11:24 Day 10 Wrap-up & Channel Resources
📂 Problem Folder & Detailed Documentation:
https://github.com/CodeByTushu/CodeByTushu-LeetCode-Solutions/tree/main/solutions/April/10-April/3740-Minimum-Distance-Between-Three-Equal-Elements-I
☕ Java Solution:
https://github.com/CodeByTushu/CodeByTushu-LeetCode-Solutions/blob/main/solutions/April/10-April/3740-Minimum-Distance-Between-Three-Equal-Elements-I/Solution.java
🐍 Python Solution:
https://github.com/CodeByTushu/CodeByTushu-LeetCode-Solutions/blob/main/solutions/April/10-April/3740-Minimum-Distance-Between-Three-Equal-Elements-I/solution.py
⚡ C++ Solution:
https://github.com/CodeByTushu/CodeByTushu-LeetCode-Solutions/blob/main/solutions/April/10-April/3740-Minimum-Distance-Between-Three-Equal-Elements-I/solution.cpp
🌐 JavaScript Solution:
https://github.com/CodeByTushu/CodeByTushu-LeetCode-Solutions/blob/main/solutions/April/10-April/3740-Minimum-Distance-Between-Three-Equal-Elements-I/solution.js
🔗 LeetCode Source Code
📌 Admin type the link
🌐 All LeetCode Solutions
📌 https://codebytushu.com/Leetcode/
📱 Join CodeByTushu on WhatsApp
Get coding updates, LeetCode solutions, daily questions and more.
https://whatsapp.com/channel/0029Vb8k5mCDeON2Xwlkxe40
❤️ Donate
📌 https://codebytushu.com/Leetcode/donate.php
🔥 Perfect For
LeetCode Easy Problems
Java DSA Preparation
Hash Table & Index Tracking
Mathematical Simplifications
Array Triplet Patterns
Time Complexity Optimization
Coding Interview Preparation
Problem Solving
🌐 Follow CodeByTushu
▶️ YouTube: https://www.youtube.com/@codebytushu
📸 Instagram: https://instagram.com/codebytushu/
💼 LinkedIn: https://www.linkedin.com/company/codebytushu/
🌍 Website: https://codebytushu.com
🐙 GitHub: https://github.com/CodeByTushu
❤️ Don’t Forget To
👍 Like | 💬 Comment | 🔔 Subscribe
💬 Question of the Day
Why does the intermediate index j cancel out of the distance formula for sorted indices i, j, and k?
1️⃣ Because (j - i) + (k - j) equals (k - i), making the total distance exactly 2 * (k - i)
2️⃣ Because j is always the arithmetic mean of i and k
3️⃣ Because the absolute value function ignores the middle term in all triplets
4️⃣ Because only the first and last elements in an array can be equal
#LeetCode3740 #LeetCode #MinimumDistanceBetweenThreeEqualElementsI #Java #JavaDSA #HashTable #Math #Array #DSA #CodingInterview #ProblemSolving #LeetCodeEasy #DailyLeetCode #JavaProgramming #CodeByTushu
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