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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. #define all(v) (v).begin(),(v).end()
  4.  
  5. struct TreeNode{
  6. 	int data;
  7. 	TreeNode* left;
  8. 	TreeNode* right;
  9.  
  10. 	TreeNode(int val):left(nullptr),right(nullptr),data(val){};
  11. };
  12. vector<int>postOrd(TreeNode* root){
  13. 	vector<int>post;
  14. 	if(root == nullptr)return post;
  15.  
  16. 	stack<TreeNode*>st;
  17. 	st.push(root);
  18.  
  19. 	while(!st.empty()){
  20. 		auto u = st.top();st.pop();
  21.  
  22. 		post.push_back(u->data);
  23.  
  24. 		if(u->left){
  25. 			st.push(u->left);
  26. 		}
  27.  
  28. 		if(u->right){
  29. 			st.push(u->right);
  30. 		}
  31.  
  32. 	}
  33. 	reverse(all(post));
  34. 	return post;
  35. }
  36. TreeNode* buildTree(){
  37. 	int x;
  38. 	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();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<int>post =postOrd(root);
  63. 	for(int x:post)cout<<x;
  64.  
  65. 	return 0;
  66. }
Success #stdin #stdout 0s 5320KB
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https://ideone.com/oyMWbt
language:
C++14 (gcc 8.3)
created:
3 days ago
visibility:
public

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