Largest-Positive-Integer-that-Exists-With-its-Negative.java

class Solution {
    public int findMaxK(int[] nums) {
        HashSet<Integer> viewed = new HashSet<>();
        int res = -1;

        for(int x : nums){
            if(res < Math.abs(x)){
                if(viewed.contains(-x)){
                    res = Math.abs(x);
                }
                
                else{
                    viewed.add(x);
                }
            }
        }
        return res;
    }
}