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.

Example

Given binary tree [3,9,20,null,null,15,7],

3
/ \
9  20
/  \
15   7
return its depth = 3.

Solution 1(C++)

/**
* Definition for a binary tree node.
* struct TreeNode {
*     int val;
*     TreeNode *left;
*     TreeNode *right;
*     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
static int x=[](){std::ios::sync_with_stdio(false); cin.tie(NULL); return 0; }();
class Solution {
public:
int maxDepth(TreeNode* root) {
int maxlv=0;
if(root==NULL) return maxlv;
queue<TreeNode*> q;
q.push(root);
while(!q.empty()){
maxlv++;
long len=q.size();
for(int i=0; i<len; i++){
TreeNode* temp=q.front();
q.pop();
if(temp->left) q.push(temp->left);
if(temp->right) q.push(temp->right);
}
}
return maxlv;
}
};

Solution 2(C++)

/**
* Definition for a binary tree node.
* struct TreeNode {
*     int val;
*     TreeNode *left;
*     TreeNode *right;
*     TreeNode(int
9bf0
x) : val(x), left(NULL), right(NULL) {}
* };
*/

static string opt =[](){
std::ios::sync_with_stdio(false);
cin.tie(NULL);
return "";
}();

class Solution
{
public:
int maxDepth(TreeNode* root)
{
if(!root)
return 0;

return max(maxDepth(root->left), maxDepth(root->right)) + 1;
}
};

算法分析

程序分析