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  1. #include <iostream>
  2. #include<queue>
  3. using namespace std;
  4. class node {
  5. public:
  6.     int data;
  7.     node* left;
  8.     node* right;
  9.     node(int d) {
  10.         data = d;
  11.         left = NULL;
  12.         right = NULL;
  13.     }
  14. };
  15.  
  16. node* buildTree(){
  17.     queue<node*>q;
  18.     int d;cin>>d;
  19.     if(d==-1)return NULL;
  20.     node*head=new node(d);
  21.     q.push(head);
  22.     int lc,rc;
  23.     while(!q.empty()){
  24.         node*f=q.front();
  25.         q.pop();
  26.         cin>>lc>>rc;
  27.         if(lc!=-1){
  28.             f->left=new node(lc);
  29.             q.push(f->left);
  30.         }
  31.         if(rc!=-1){
  32.             f->right=new node(rc);
  33.             q.push(f->right);
  34.         }
  35.     }
  36.     return head;
  37. }
  38.  
  39. void printPreOrder(node* &root){
  40. 	if(root==NULL)return;
  41. 	cout<<root->data<<" ";
  42. 	printPreOrder(root->left);
  43. 	printPreOrder(root->right);
  44. }
  45.  
  46. int main()
  47. {
  48.     node*root=buildTree();
  49.     printPreOrder(root);
  50. }
  51.  
Success #stdin #stdout 0.01s 5312KB
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1 2 3 4 5 -1 6 -1 -1 -1 -1 -1 -1
stdout
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https://ideone.com/Tmu1rO
language:
C++14 (gcc 8.3)
created:
4 years ago
visibility:
secret

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