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.
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
//方法一：dfs
class Solution {
public:
int maxDepth(TreeNode* root) {
if(root==NULL)
return 0;
else
return max(maxDepth(root->left),maxDepth(root->right))+1;
}
};
//方法二：bfs
class Solution {
public:
int maxDepth(TreeNode* root) {
if(root==NULL)
return 0;
queue<TreeNode*>q;
q.push(root);
int res=0;
int n;
while(!q.empty())
{
res++;
for(int i=0,n=q.size();i<n;i++)
{
TreeNode*p=q.front();
q.pop();
if(p->left!=NULL)
q.push(p->left);
if(p->right!=NULL)
q.push(p->right);
}
}
return res;
}
};
