/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
class Solution {

    int moves = 0;

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

    private int distribute(TreeNode node) {
        if(node == null) {
            return 0;
        }

        int coinsLeft = distribute(node.left);      // 1
        int coinsRight = distribute(node.right);    // 1
        int coinsNode = node.val;                   // 1
        int coinsTotal = coinsLeft + coinsRight + coinsNode;

        moves += Math.abs(coinsLeft) + Math.abs(coinsRight);

        return coinsTotal - 1;
    }

}