257. Binary Tree Paths

Given a binary tree, return all root-to-leaf paths.

Note: A leaf is a node with no children.

Example:

Input:

   1
 /   \
2     3
 \
  5

Output: ["1->2->5", "1->3"]

Explanation: All root-to-leaf paths are: 1->2->5, 1->3

​

private List<string> list = new List<string>();
        public IList<string> BinaryTreePaths(TreeNode root)
        {
            if (root == null)
            {
                return list;
            }
            else
            {
                Chuck(string.Empty, root);
            }

            return list;
        }

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

            if (str.Equals(string.Empty))
            {
                str = $"{node.val}";
            }
            else
            {
                str = $"{str}->{node.val}";
            }

            if (node.left == null && node.right == null)
            {
                list.Add(str);
            }
            else
            {
                Chuck(str, node.left);
                Chuck(str, node.right);
            }
        }

 

Runtime: 264 ms, faster than 53.41% of C# online submissions for Binary Tree Paths.

Memory Usage: 30 MB, less than 24.53% of C# online submissions forBinary Tree Paths.