Contains Duplicate

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

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