szjy_6_树_006

阅读代码，程序输出是（ ）。

#include <iostream>
using namespace std;

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

void visit(Node* root) {
if (root == nullptr) return;
cout << root->value;
visit(root->left);
visit(root->right);
}

int main() {
Node m{'M'}, f{'F'}, t{'T'}, h{'H'}, r{'R'};
m.left = &f;  m.right = &t;
f.right = &h;
t.left = &r;
visit(&m);
}

{{ select(1) }}

• FHMRT
• MFHTR
• HFMRT
• MFRTH