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  1. #include <algorithm>
  2. #include <iostream>
  3. #include <vector>
  4.  
  5. struct Node {
  6.     Node(int x) {
  7.         key = x;
  8.         left = nullptr;
  9.         right = nullptr;
  10.     }
  11.     int key;
  12.     Node* left;
  13.     Node* right;
  14. };
  15. Node* BSTConstruction(const std::vector<int>& preorder, int& index, int low, int high) {
  16.     if (index >= preorder.size()) {
  17.         return nullptr;
  18.     }
  19.     int current_key = preorder[index];
  20.     if (current_key <= low || current_key > high) {
  21.         return nullptr;
  22.     }
  23.     Node* current_node = new Node(current_key);
  24.     index++;
  25.     current_node->left = BSTConstruction(preorder, index, low, current_key);
  26.     current_node->right = BSTConstruction(preorder, index, current_key, high);
  27.     return current_node;
  28. }
  29. void InOrder(const Node* node) {
  30.     if (node == nullptr) {
  31.         return;
  32.     }
  33.     InOrder(node->left);
  34.     std::cout << node->key << ' ';
  35.     InOrder(node->right);
  36. }
  37. void PostOrder(const Node* node) {
  38.     if (node == nullptr) {
  39.         return;
  40.     }
  41.     PostOrder(node->left);
  42.     PostOrder(node->right);
  43.     std::cout << node->key << ' ';
  44. }
  45. void PrintPostIn(const Node* root) {
  46.     PostOrder(root);
  47.     std::cout << '\n';
  48.     InOrder(root);
  49. }
  50. void PostOrderDelete(Node* root) {
  51.     if (root == nullptr) {
  52.         return;
  53.     }
  54.     PostOrderDelete(root->left);
  55.     PostOrderDelete(root->right);
  56.     root->left = nullptr;
  57.     root->right = nullptr;
  58.     //delete root;
  59. }
  60. int main() {
  61.     std::ios_base::sync_with_stdio(false);
  62.     std::cin.tie(NULL);
  63.     int num;
  64.     int index = 0;
  65.     std::cin >> num;
  66.     std::vector<int> keys(num);
  67.     for (int i = 0; i != num; i++) {
  68.         std::cin >> keys[i];
  69.     }
  70.     Node* root = BSTConstruction(keys, index, -1, 1000000000);
  71.     PrintPostIn(root);
  72.     PostOrderDelete(root);
  73.     return 0;
  74. }
Success #stdin #stdout 0.01s 5276KB
comments (?)
stdin 
7
4 2 1 3 6 5 7
stdout 
1 3 2 5 7 6 4 
1 2 3 4 5 6 7
https://ideone.com/nLiNM2
language:
C++ (gcc 8.3)
created:
7 days ago
visibility:
public

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