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.
求二叉树的最大深度问题用到深度优先搜索DFS，递归的完美应用，跟求二叉树的最小深度问题原理相同。代码如下：
/** * Definition for binary tree * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */ class Solution { public: int maxDepth(TreeNode *root) { if (root == NULL) return 0; if (root->left == NULL && root->right == NULL) return 1; if (root->left == NULL) return 1 + maxDepth(root->right); else if (root->right == NULL) return 1 + maxDepth(root->left); else return 1 + max(maxDepth(root->left), maxDepth(root->right)); } };
求二叉树的最小深度可以参见我的博文：
http://www.cnblogs.com/grandyang/p/4042168.html
Maximum Depth of Binary Tree 二叉树的最大深度
原文：http://www.cnblogs.com/grandyang/p/4051348.html