0217. Contains Duplicate.js

// Given an array of integers, find if the array contains any duplicates.
//
// Your function should return true if any value appears at least twice in the array, and it should return false if every element is distinct.
//
// Example 1:
//
// Input: [1,2,3,1]
// Output: true
//
// Example 2:
//
// Input: [1,2,3,4]
// Output: false
//
// Example 3:
//
// Input: [1,1,1,3,3,4,3,2,4,2]
// Output: true

/**
 * @param {number[]} nums
 * @return {boolean}
 */

// Hashset
// Time O(n)
// Space O(n)
const containsDuplicate = (nums) => {
  const set = new Set();
  for (const n of nums) {
    if (set.has(n)) return true;
    set.add(n);
  }
  return false;
};