fork download
copy 
  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. struct TreeNode{
  4. 	int val;
  5. 	TreeNode* right;
  6. 	TreeNode* left;
  7. 	TreeNode(int val):left(nullptr),right(nullptr),val(val){};
  8. };
  9.  
  10. vector<int>top(TreeNode* root){
  11.   vector<int>ans;
  12.   if(root == nullptr)return ans;
  13.    map<int,int>mp;
  14.   queue<pair<TreeNode*,int>>q;
  15.   q.push({root,0});
  16.  
  17.   while(!q.empty()){
  18.   	auto [u,v]= q.front();
  19.   	q.pop();
  20.   	if(mp.find(v)==mp.end()){
  21.   		mp[v]=u->val;
  22.   	}
  23.   	if(u->left){
  24.   		q.push({u->left,v-1});
  25.   	}
  26.  
  27.   	if(u->right){
  28.   		q.push({u->right,v+1});
  29.   	}
  30.   }
  31.  
  32.   for(auto [v,val]:mp){
  33.   	ans.push_back(val);
  34.   }
  35.   return ans;
  36. }
  37. TreeNode* buildTree(){
  38. 	int x;cin>>x;
  39. 	if(x==-1)return nullptr;
  40. 	TreeNode* root = new TreeNode(x);
  41.  
  42. 	queue<TreeNode*>q;
  43. 	q.push(root);
  44.  
  45. 	while(!q.empty()){
  46. 		auto u = q.front();
  47. 		q.pop();
  48.  
  49. 		if(cin>>x && x!=-1){
  50. 			u->left = new TreeNode(x);
  51. 			q.push(u->left);
  52. 		}
  53.  
  54. 		if(cin>>x && x!=-1){
  55. 			u->right = new TreeNode(x);
  56. 			q.push(u->right);
  57. 		}
  58. 	}
  59. 	return root;
  60. }
  61. int main() {
  62.     TreeNode* root = buildTree();
  63.    vector<int>ans = top(root);
  64.  
  65.     for(auto x : ans){
  66.  
  67.     	cout<<x<<endl;
  68.     }
  69. 	return 0;
  70. }
Success #stdin #stdout 0.01s 5312KB
comments (?)
stdin
copy 
1 2 3 4 5 6 7
stdout
copy 
4
2
1
3
7
https://ideone.com/A3SIxQ
language:
C++14 (gcc 8.3)
created:
1 day ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!