public int maxDepth(TreeNode root)
{
if (root == null) { return 0; }
int result = this.maxDepth(root.left);
result = Math.Max(result,
this.maxDepth(root.right)
);
result++; // add current level
return result;
}
static void Main(string[] args)
{
TreeNode test = new TreeNode(1);
test.right = new TreeNode(2);
TreeNode current = test.right;
current.left = new TreeNode(3);
current = current.left;
current.right = new TreeNode(4);
Solution s = new Solution();
Console.Out.WriteLine("Solution:{0}", s.maxDepth(test));
}
