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.
解题方法是使用递归，最大深度就是 左子树的最大深度 与 右子树最大深度 的最大值+1。
1 /** 2 * Definition for binary tree 3 * public class TreeNode { 4 * int val; 5 * TreeNode left; 6 * TreeNode right; 7 * TreeNode(int x) { val = x; } 8 * } 9 */ 10 public class Solution { 11 public int maxDepth(TreeNode root) { 12 if (root==null) { 13 return 0; 14 } 15 if (root.left==null && root.right==null) { 16 return 1; 17 } 18 return 1+Math.max(maxDepth(root.left), maxDepth(root.right)); 19 } 20 }
LeetCode Maximum Depth of Binary Tree
原文：http://www.cnblogs.com/birdhack/p/3973988.html