剑指 Offer 32 - I. 从上到下打印二叉树
题目链接
class Solution {
public:
vector<int> levelOrder(TreeNode* root) {
if(!root) return {
};
queue<TreeNode*> queue;
vector<int> res;
queue.push(root);
while(!queue.empty()){
TreeNode* cur=queue.front();
queue.pop();
res.push_back(cur->val);
if(cur->left){
queue.push(cur->left);
}
if(cur->right){
queue.push(cur->right);
}
}
return res;
}
};
剑指 Offer 32 - II. 从上到下打印二叉树 II
题目链接
class Solution {
public:
vector<vector<int>> levelOrder(TreeNode* root) {
if(!root) return {
};
queue<TreeNode*> queue;
queue.push(root);
vector<vector<int>> res;
while(!queue.empty()){
int l=queue.size();
vector<int> tmp;
for(int i=0;i<l;i++){
TreeNode* cur=queue.front();
queue.pop();
tmp.push_back(cur->val);
if(cur->left){
queue.push(cur->left);
}
if(cur->right){
queue.push(cur->right);
}
}
res.push_back(tmp);
}
return res;
}
};
剑指 Offer 32 - III. 从上到下打印二叉树 III
题目链接
class Solution {
public:
vector<vector<int>> levelOrder(TreeNode* root) {
if(!root) return {
};
queue<TreeNode*> queue;
queue.push(root);
vector<vector<int>> res;
int flag=0;
while(!queue.empty()){
int l=queue.size();
vector<int> tmp;
for(int i=0;i<l;i++){
TreeNode* cur=queue.front();
queue.pop();
tmp.push_back(cur->val);
if(cur->left){
queue.push(cur->left);
}
if(cur->right){
queue.push(cur->right);
}
}
if(flag&1==1){
reverse(tmp.begin(),tmp.end());
}
res.push_back(tmp);
flag++;
}
return res;
}
};