输入：arr = [3,1,3,6]
输出：false

输入：arr = [2,1,2,6]
输出：false

输入：arr = [4,-2,2,-4]
输出：true
解释：可以用 [-2,-4] 和 [2,4] 这两组组成 [-2,-4,2,4] 或是 [2,4,-2,-4]

输入：arr = [1,2,4,16,8,4]
输出：false

class Solution {
    public boolean canReorderDoubled(int[] A) {
        Map<Integer, Integer> count = new HashMap<>();
        for (int x : A)
            count.put(x, count.getOrDefault(x, 0) + 1);

        Integer[] B = new Integer[A.length];
        for (int i = 0; i < A.length; ++i)
            B[i] = A[i];
        Arrays.sort(B, Comparator.comparingInt(Math::abs));

        for (int x : B) {
            if (count.get(x) == 0) continue;
            if (count.getOrDefault(2 * x, 0) <= 0) return false;
            
            count.put(x, count.get(x) - 1);
            count.put(2 * x, count.get(2 * x) - 1);
        }
        return true;
    }
}