Xóa cây nhị phân bằng từ khóa delete trong C++

Định nghĩa nút cây nhị phân bằng lớp chứa dữ liệu và hai con trỏ trái/phải:

class btree_node {
public:
    int data;
    btree_node* leftChild;
    btree_node* rightChild;
};

Hàm tạo khởi tạo nút mới:

btree_node(int data) {
    this->data = data;
    this->leftChild = NULL;
    this->rightChild = NULL;
}

Hàm hủy (destructor) dùng delete để giải phóng đệ quy hai con:

~btree_node() {
    delete leftChild;
    delete rightChild;
    cout << this->data << " is being deleted" << endl;
}

Gọi delete root; để xóa toàn bộ cây.

Ví dụ hoàn chỉnh

#include <iostream>
using namespace std;

class btree_node {
public:
    int data;
    btree_node* leftChild;
    btree_node* rightChild;
    btree_node(int data) {
        this->data = data;
        this->leftChild = NULL;
        this->rightChild = NULL;
    }
    ~btree_node() {
        delete leftChild;
        delete rightChild;
        cout << this->data << " is being deleted" << endl;
    }
};

int main() {
    btree_node* root = new btree_node(2);
    btree_node* node1 = new btree_node(4);
    btree_node* node2 = new btree_node(6);
    btree_node* node3 = new btree_node(8);
    btree_node* node4 = new btree_node(10);
    root->leftChild = node1;
    root->rightChild = node2;
    node1->leftChild = node3;
    node1->rightChild = node4;
    delete root;
    return 0;
}

Kết quả

8 is being deleted
10 is being deleted
4 is being deleted
6 is being deleted
2 is being deleted