Valid Anagram

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

class Solution {
  public boolean containsDuplicate(int[] nums) {
    HashSet<Integer> uniques = new HashSet<>();
    for (int num : nums) {
      if (uniques.contains(num)) {
        return true;
      }
      uniques.add(num);
    }
    return false;
  }
}