Contains Duplicate

Given an integer array nums, return true if any value appears at least twice in the array, and return false if every element is distinct

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Brute Force Approach
Time Complexity : O(n^2)
Space Complexity : O(1)

Sort Approach
Time Complexity : O(nlogn)
Space Complexity : O(1)

Optimized Approach via hash

var containsDuplicate = function (nums) {
    let hashMap = {};
    for (let num of nums) {
        if (num in hashMap) {
            return true;
        }
        hashMap[num] = 1;
    }
    return false;
}

Time Complexity : O(n)
Space Complexity : O(n)