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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. struct TreeNode{
  4. int data;
  5. TreeNode* left;
  6. TreeNode* right;
  7. TreeNode(int val):left(nullptr),right(nullptr),data(val){};
  8. };
  9.  
  10. vector<vector<int>>level(TreeNode* root){
  11. 	vector<vector<int>>ans;
  12. 	queue<TreeNode*>q;
  13. 	if(root == nullptr){
  14. 		return ans;
  15. 	}
  16.  
  17. 	q.push(root);
  18.  
  19. 	while(!q.empty()){
  20. 		int size = q.size();
  21. 		vector<int>lvl;
  22. 		for(int i = 0;i< size;i++){
  23. 			auto u=q.front();q.pop();
  24. 			lvl.push_back(u->data);
  25. 			if(u->left){
  26. 				q.push(u->left);
  27. 			}
  28.  
  29. 			if(u->right){
  30. 				q.push(u->right);
  31. 			}
  32. 		}
  33. 		ans.push_back(lvl);
  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. 	queue<TreeNode*>q;
  42. 	q.push(root);
  43.  
  44. 	while(!q.empty()){
  45. 		auto u = q.front();
  46. 		q.pop();
  47.  
  48. 		if(cin>>x && x!= -1){
  49. 			u->left = new TreeNode(x);
  50. 			q.push(u->left);
  51. 		}
  52.  
  53. 			if(cin>>x && x!= -1){
  54. 			u->right = new TreeNode(x);
  55. 			q.push(u->right);
  56. 		}
  57. 	}
  58. 	return root;
  59. }
  60. int main() {
  61.     TreeNode* root = buildTree();
  62.     vector<vector<int>>ans = level(root);
  63.    // Clean range-based iteration
  64.     for (const auto& lvl : ans) {
  65.         for (int val : lvl) {
  66.             cout << val << " ";
  67.         }
  68.         cout << "\n";
  69.     }
  70. 	return 0;
  71. }
Success #stdin #stdout 0.01s 5280KB
comments (?)
stdin
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3 9 20 -1 -1 15 7
stdout
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3 
9 20 
15 7
https://ideone.com/wzQVLF
language:
C++14 (gcc 8.3)
created:
3 days ago
visibility:
public

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