113. Path Sum II

Given a binary tree and a sum, find all root-to-leaf paths where each path's sum equals the given sum.

Note: A leaf is a node with no children.

Example:

Given the below binary tree and sum = 22,

      5
     / 
    4   8
   /   / 
  11  13  4
 /      / 
7    2  5   1

Return:

[
   [5,4,11,2],
   [5,8,4,5]
]

 -

 private List<IList<int>> list = new List<IList<int>>();

        public IList<IList<int>> PathSum(TreeNode root, int sum)
        {
            Chuck(root, sum, 0, string.Empty);
            return list;
        }

        private void Chuck(TreeNode node, int sum, int tempSum, string str)
        {
            if (node == null)
            {
                return;
            }

            tempSum = tempSum + node.val;
            var left = node.left;
            var right = node.right;
            if (string.IsNullOrEmpty(str))
            {
                str = $"{node.val}";
            }
            else
            {
                str = $"{str},{node.val}";
            }

            if (left == null && right == null)
            {
                if (tempSum == sum)
                {
                    var tempList = str.Split(',').Select(x => Convert.ToInt32(x)).ToList();
                    list.Add(tempList);
                }
            }
            else
            {
                Chuck(left, sum, tempSum, str);
                Chuck(right, sum, tempSum, str);
            }
        }

Runtime: 288 ms, faster than 21.95% of C# online submissions for Path Sum II.

Memory Usage: 34.2 MB, less than 13.98% of C# online submissions forPath Sum II.