104. Maximum Depth of Binary Tree

Given a binary tree, find its maximum depth.

The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.

class Solution {

    public int maxDepth(TreeNode root) {

        if (root == null)

            return 0;

       int left = maxDepth(root.left);

       int right= maxDepth(root.right);

       return 1 + Math.max(left, right);

    }

}