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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  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. // this is same as bfs
  17.  
  18. Node* buildTree(){
  19.  
  20. queue<Node*>q;
  21.  
  22. int d;cin>>d;
  23.  
  24. // if -1 return null
  25.  
  26. if(d==-1)return NULL;
  27.  
  28. // else make node and push to queue
  29.  
  30. Node*head=new Node(d);
  31.  
  32. q.push(head);
  33.  
  34. int lc,rc;
  35.  
  36. // now till the queue is not empty pop and push the children if next input is not -1
  37.  
  38. while(!q.empty()){
  39.  
  40.     Node*f=q.front();
  41.  
  42.     q.pop();
  43.  
  44.     cin>>lc>>rc;
  45.  
  46.     if(lc!=-1){
  47.  
  48.         f->left=new Node(lc);
  49.  
  50.         q.push(f->left);
  51.  
  52.     }
  53.  
  54.     if(rc!=-1){
  55.  
  56.         f->right=new Node(rc);
  57.  
  58.         q.push(f->right);
  59.  
  60.     }
  61.  
  62. }
  63.  
  64. // finally return head
  65.  
  66. return head;
  67. }
  68.  
  69.  
  70. void print_left_side(Node*root, int level, int &maxlevel){
  71.     if(root==NULL){
  72.         return;
  73.     }
  74.  
  75.     if(maxlevel<level){
  76.         cout<<root->data<<" ";
  77.         maxlevel = level;
  78.     }
  79.  
  80.     print_left_side(root->left, level+1, maxlevel);
  81.     print_left_side(root->right, level+1, maxlevel);
  82. }
  83.  
  84.  
  85. int main(){
  86.     Node*root = buildTree();
  87.     int maxLevel = -1;
  88.     int maxLevel2 = -1;
  89.     print_left_side(root,0,maxLevel2);
  90. }
Success #stdin #stdout 0.01s 5516KB
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https://ideone.com/QC0NUL
language:
C++ (gcc 8.3)
created:
3 years ago
visibility:
public

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