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.

Example:

Input: nums = [1,2,3,1]

Output: true

Constraints:

1 <= nums.length <= 10^5

-10^9 <= nums[i] <= 10^9

Solution in JavaScript

var containsDuplicate = function(nums) {
    let contains = false;

    for (let i = 0; i < nums.length; i++) {
        for (let j = 0; j < nums.length; j++) {
            if (i !== j && nums[i] === nums[j]) {
                contains = true;
                break;
            }
        }
    }
    return contains;
};