1. 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.

• Create Set loop through array if it exists then true else false
• Time: O(n) Space: O(n)

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