letecode [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.
Note: A leaf is a node with no children.
Example:
Given binary tree [3,9,20,null,null,15,7],
3 / \ 9 20 / \ 15 7
return its depth = 3.
题目大意:
给定一个二叉树,计算二叉树的深度
理解:
根节点为空,深度为0;根节点左右子树为空,深度为1。
每递归一层深度+1.
代码C++:
/** * Definition for a binary tree node. * 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; int left = maxDepth(root->left); int right = maxDepth(root->right); return left>right?left+1:right+1; } };
运行结果:
执行用时 : 12 ms 内存消耗 : 19.3 MB