LeetCode 3116 (Hard) — binary search + inclusion-exclusion makes it easy

Shaan Yadav — Fri, 21 Aug 2026 09:53:53 +0000

Full walkthrough: https://www.youtube.com/watch?v=vFuFA3ByCs0

LeetCode 3116 — Kth Smallest Amount With Single Denomination Combination. Here’s the trick everyone misses:

Brute force (generate all multiples, pick k-th) fails because k can reach 2×10⁹.

The real approach:

Binary search the answer X
Count valid amounts ≤ X using inclusion-exclusion
Odd subsets add, even subtract (bitmask over coins)
LCM via GCD, break when LCM > X
O(n · 2ⁿ · log(k·M)) — passes cleanly.

The 26% acceptance rate makes this look harder than it is. Once you see the count(X) monotonic trick, it clicks.

Started Writing Technical Articles on Medium — First Article on Sliding Window Algorithm in Java!

Shaan Yadav — Sat, 17 May 2025 07:59:05 +0000

Hey fellow developers! 👋

I’m excited to share that I’ve recently started writing technical articles on Medium to document and share my learning journey.

This all began after attending an inspiring session by Anu Sharma at the KIET Technoverse event, where I was encouraged to showcase my projects and concepts through writing.

To kick things off, I wrote a detailed guide on solving the Smallest Distinct Window problem using the sliding window algorithm in Java — a classic but tricky coding interview problem.

In the article, I cover:

Understanding the problem step-by-step

Brute force and optimized sliding window approaches

Detailed Java code snippets with explanations

Time and space complexity analysis

If you’re prepping for interviews or want to strengthen your string and hashmap skills, this might be helpful!

🔗 Check out the full article here on Medium

I’m looking forward to writing more and would love your feedback and suggestions!

Happy coding! 🚀

DEV Community: Shaan Yadav

LeetCode 3116 (Hard) — binary search + inclusion-exclusion makes it easy

Started Writing Technical Articles on Medium — First Article on Sliding Window Algorithm in Java!