---
title: "Discussion on \"Everyone uses a HashSet for LeetCode 961. I found a way to use O(1) space by hacking Moore's Voting Algorithm. Here is the math behind it.\" | Hashnode"
description: "Discussion on \"Everyone uses a HashSet for LeetCode 961. I found a way to use O(1) space by hacking Moore's Voting Algorithm. Here is the math behind it.\". LeetCode 961: N-Repeated Element in Size 2N Array is usually solved with a simple Hash Set (O(N) space) or randomized checks. But recently, I challenged myself to solve it deterministically using O(1) space.\nThe result? A modified version of Moore’s ..."
url: "https://hashnode.com/posts/everyone-uses-a-hashset-for-leetcode-961-i-found-a-way-to-use-o1-space-by-hacking-moores-voting-algorithm-here-is-the-math-behind-it/69579b40f591e14a80762e07"
---

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# [Everyone uses a HashSet for LeetCode 961. I found a way to use O(1) space by hacking Moore's Voting Algorithm. Here is the math behind it.](https://pranay180825.hashnode.dev/everyone-uses-a-hashset-for-leetcode-961-i-found-a-way-to-use-o1-space-by-hacking-moores-voting-algorithm-here-is-the-math-behind-it?utm_source=hashnode&utm_medium=feed)

LeetCode 961: N-Repeated Element in Size 2N Array is usually solved with a simple Hash Set (O(N) space) or randomized checks. But recently, I challenged myself to solve it deterministically using O(1) space. The result? A modified version of Moore’s ...

Jan 2 · 3 min read · pranay180825.hashnode.dev  
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