104. Maximum Depth of Binary Tree
题意
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.
递归解法
class Solution {
public:
int maxDepth(TreeNode* root) {
if(root == NULL) return 0;
return max(maxDepth(root->left), maxDepth(root->right))+1;
}
};
非递归解法
class Solution {
public:
int maxDepth(TreeNode* root) {
if(root == NULL)
return 0;
else root->val = 1;
queue<TreeNode*> q;
q.push(root);
while(!q.empty())
{
TreeNode* curNode = q.front();
q.pop();
if(q.empty() && !curNode->left && !curNode->right)
return curNode->val;
if(curNode->left)
{
curNode->left->val = curNode->val+1;
q.push(curNode->left);
}
if(curNode->right)
{
curNode->right->val = curNode->val+1;
q.push(curNode->right);
}
}
}
};
