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$ curl repovive.com/roadmaps/math-fundamentals/big-o-notation/contains-duplicate-implementation

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$ curl repovive.com/roadmaps/math-fundamentals/big-o-notation/contains-duplicate-implementation

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Contains Duplicate - Implementation - Big O Notation | Math Fundamentals | Repovive

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Math Fundamentals18 sections · 842 units13h total

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Contains Duplicate - Implementation

The pseudocode

Here is the optimal hash set solution:


function containsDuplicate(nums)
    seen := empty hash set
    for each num in nums
        if num in seen then
            return true
        add num to seen
    return false

Time: $O(n)$ since hash set operations are $O(1)$ average. Space: $O(n)$ for the set. This is the best time complexity possible since you must examine each element at least once.