217. Contains Duplicate

Problem

Tags: Array, Hash Table, Sorting

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 <= 10^5
• -10^9 <= nums[i] <= 10^9

Code

JS

// 217. Contains Duplicate (12/23/53712)
// Runtime: 68 ms (94.68%) Memory: 44.73 MB (94.80%) 

/**
 * @param {number[]} nums
 * @return {boolean}
 */
function containsDuplicate(nums) {
    const set = new Set();
    for (const n of nums) {
        if (set.has(n)) return true;
        set.add(n);
    }
    return false;
}