Contains Duplicate

Description

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 1:

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

Example 2:

Input: nums = [1,2,3,4]
Output: false

Example 3:

Input: nums = [1,1,1,3,3,4,3,2,4,2]
Output: true

 

Constraints:

• 1 <= nums.length <= 105
• -109 <= nums[i] <= 109

Solution(javascript)

/**
 * @param {number[]} nums
 * @return {boolean}
 */
var containsDuplicate = function(nums) {
    let seen = {};
    for (let i = 0; i < nums.length; i++) {
        if(seen[nums[i]]) {
            return true;
        } else {
            seen[nums[i]] = 1;
        }
    }
    return false;
};