AcWing 45. 之字形打印二叉树
原题链接
中等
作者:
heiyou
,
2020-04-27 19:35:37
,
所有人可见
,
阅读 586
滚动数组:每次用vector<int>保存当前这一层的遍历结果
用当前这一层的遍历结果去拓展下一层
/**
* 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:
vector<int> get_val(vector<TreeNode *> level){
vector<int> res;
for(auto u : level){
res.push_back(u -> val);
}
return res;
}
vector<vector<int>> printFromTopToBottom(TreeNode* root) {
int flag = 1;
vector<vector<int>> res;
if(!root) return res;
vector<TreeNode *> level;
level.push_back(root);
while(true)
{
if(flag == 1) res.push_back(get_val(level));
else if(flag == -1)
{
vector<int> tmp = get_val(level);
reverse(tmp.begin(), tmp.end());
res.push_back(tmp);
}
vector<TreeNode *> NewLevel;
for(auto u : level)
{
if(u -> left) NewLevel.push_back(u -> left);
if(u -> right) NewLevel.push_back(u -> right);
}
if(NewLevel.size())
{
flag = 0 - flag;
level = NewLevel;
}
else break;
}
return res;
}
};