szjy_6_树_002

阅读下面的 C++ 代码，程序输出是（ ）。

#include <iostream>
using namespace std;

struct Node {
int value;
Node* left = nullptr;
Node* right = nullptr;
};

int leafCount(Node* root) {
if (root == nullptr) return 0;
if (root->left == nullptr && root->right == nullptr) return 1;
return leafCount(root->left) + leafCount(root->right);
}

int main() {
Node a{1}, b{2}, c{3}, d{4}, e{5}, f{6};
a.left = &b;  a.right = &c;
b.left = &d;
c.left = &e;  c.right = &f;
cout << leafCount(&a);
}

{{ select(1) }}

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