import java.util.HashSet;

class Solution {
	public boolean containsDuplicate(int[] nums) {
		HashSet<Integer> numSet  = new HashSet<>();
    
		for (int i = 0; i < nums.length; i++) {

			if (numSet.contains(nums[i])) {
				return true;
			}
			numSet.add(nums[i]);
		}
    
		return false;
	}
}
