class Solution {
    public int[] fairCandySwap(int[] a, int[] b) {
        int sumA = 0, sumB = 0;
        for(int n: a) sumA+=n;
        for(int n: b) sumB+=n;
        
        int delta = (sumB - sumA) / 2;
        
        Set<Integer> set = new HashSet<>();
        for(int n: b) set.add(n);
        
        for(int n: a)
            if(set.contains(n+delta)) return new int[]{n, n+delta};
        
        return new int[0];
    }
}