979. Distribute Coins in Binary Tree - solution I wrote in the contest on Jan. 19, 2019. The solution is not working

979DistributeCoinsInBinaryTree.cs

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     public int val;
 *     public TreeNode left;
 *     public TreeNode right;
 *     public TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public int DistributeCoins(TreeNode root)
        {
            var list = new List<int>();
            inorderTraversal(root, list);

            var length = list.Count;

            int coinsMove = 0;
            var zeroPositions = new List<int>();
            var CoinPositions = new List<int>();
            
            for(int i = 0; i < length; i++)
            {
                if(list[i] == 0)
                {
                    zeroPositions.Add(i);
                }
                else if(list[i] > 1)
                {
                    CoinPositions.Add(i);
                }
            }

            int zeroIndex = 0;
            int coinIndex = 0;
            while(zeroIndex < zeroPositions.Count &&
                  coinIndex < CoinPositions.Count)
            {
                var coinPosition = CoinPositions[coinIndex];
                var zeroPosition = zeroPositions[zeroIndex];

                coinsMove += Math.Abs(coinPosition - zeroPosition);
                zeroIndex++;
                list[coinPosition]--;
                if(list[coinPosition] == 1)
                {
                    coinIndex++;
                }
            }

            return coinsMove;
        }

        private static void inorderTraversal(TreeNode root, List<int> list)
        {
            if (root == null)
                return;
            inorderTraversal(root.left, list);
            list.Add(root.val);
            inorderTraversal(root.right, list);
        }
}