// Runtime: 0 ms
class Solution {
    int moves;

    public int distributeCoins(TreeNode root) {
        b(root);
        return moves;
    }

    private int b(TreeNode root){
        if (root == null) return 0;

        root.val += b(root.left) + b(root.right) - 1;
        moves += Math.abs(root.val);

        return root.val;
    }
}