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  1.   #include <iostream>
  2. #include <stack>
  3. using namespace std;
  4.  
  5. struct Node{
  6.     int data;
  7.     Node *left, *right;
  8.     Node (int val) {
  9.         data = val;
  10.         left = NULL;
  11.         right = NULL;
  12.     }
  13. };
  14.  
  15. void zigzag(Node *root) {
  16.     if(root == NULL) return;
  17.  
  18.     stack<Node*> current;
  19.     stack<Node*> next;
  20.  
  21.     bool leftToRight = true;
  22.     current.push(root);
  23.  
  24.     while(!current.empty()) {
  25.         Node *temp = current.top();
  26.         current.pop();
  27.  
  28.         if(temp) {
  29.             cout << temp->data << " ";
  30.  
  31.             if(leftToRight) {
  32.                 if(temp->left)
  33.                     next.push(temp->left);
  34.                 if(temp->right)
  35.                     next.push(temp->right);
  36.             }
  37.             else {
  38.                 if(temp->right)
  39.                     next.push(temp->right);
  40.                 if(temp->left)
  41.                     next.push(temp->left);
  42.             }
  43.         }
  44.         if(current.empty()) {
  45.             leftToRight = !leftToRight;
  46.             swap(current, next);
  47.         }
  48.     }
  49. }
  50.  
  51. int main() {
  52.     /*
  53.         12
  54.        / \
  55.       9   15
  56.      / \
  57.     5  10
  58.     */
  59.     Node *root = new Node(12);
  60.     root->left = new Node(9);
  61.     root->right = new Node(15);
  62.     root->left->left = new Node(5);
  63.     root->left->right = new Node(10);
  64.  
  65.     zigzag(root);  
  66.     cout << endl;
  67.  
  68.     return 0;
  69. }
  70.  
Success #stdin #stdout 0.01s 5276KB
comments (?)
stdin 
Standard input is empty
stdout 
12 15 9 5 10
https://ideone.com/D834Zu
language:
C++ (gcc 8.3)
created:
15 days ago
visibility:
public

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