c++统计二叉搜索树的节点数

以下是C++统计二叉搜索树节点数的代码实现：

#include <iostream>
using namespace std;

// 定义二叉搜索树节点结构体
struct TreeNode {
    int val;
    TreeNode* left;
    TreeNode* right;
    TreeNode(int x) : val(x), left(NULL), right(NULL) {}
};

// 统计二叉搜索树节点数
int countNodes(TreeNode* root) {
    if (root == NULL) {
        return 0;    }
    return 1 + countNodes(root->left) + countNodes(root->right);
}

int main() {
    // 构建二叉搜索树
    TreeNode* root = new TreeNode(4);
    root->left = new TreeNode(2);
    root->right = new TreeNode(6);
    root->left->left = new TreeNode(1);
    root->left->right = new TreeNode(3);
    root->right->left = new TreeNode(5);
    root->right->right = new TreeNode(7);

    // 统计节点数并输出
    int count = countNodes(root);
    cout << "The number of nodes in the binary search tree is: " << count << endl;

    return 0;
}