containsDuplicate = (nums) => {
    for (let right = 0; right < nums.length; right++) {/* Time O(N) */
        for (let left = 0; left < right; left++) {         /* Time O(N) */
            const isDuplicate = nums[left] === nums[right];
            if (isDuplicate) return true;
        }
    }

    return false;
}
Brute Force - Linear Search
Time O(N^2) | Space O(1)
https://leetcode.com/problems/contains-duplicate/
@param {number[]} nums
@return {boolean}