HackMD
【LeetCode】 104. Maximum Depth of Binary Tree
Description
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.
給一棵二元樹，找到它最大深度。
最大深度代表從樹根到最遠樹葉的距離。
提示：樹葉指一個沒有小孩的節點。
Example:
Given binary tree [3,9,20,null,null,15,7],
3
/ \
9 20
/ \
15 7
return its depth = 3.
Solution
- 用一個變數代表最深深度，一個變數代表現在深度，跑DFS即可。
Code
/**
* 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:
void FindDepth(TreeNode* node, int nowdepth,int &depth)
{
if(!node)return;
depth = max(depth,nowdepth);
FindDepth(node->left,nowdepth+1,depth);
FindDepth(node->right,nowdepth+1,depth);
}
int maxDepth(TreeNode* root) {
int depth=0;
FindDepth(root,1,depth);
return depth;
}
};
