LeetCode_104Maximum 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.

可以采用递归，DFS

     public int maxDepth(TreeNode root) {            if (root == null) return 0;            int l = maxDepth(root.left);            int r = maxDepth(root.right);            return l > r? l+1:r+1;          }