这我课后作业

嗨嗨嗨

#include <iostream>
#include <string>
using namespace std;

struct FBI_Node {
    char type;
    FBI_Node* left;
    FBI_Node* right;
    FBI_Node(char t) : type(t), left(nullptr), right(nullptr) {}
};

char determine_type(const string& s) {
    bool has_zero = false;
    bool has_one = false;
    for (char c : s) {
        if (c == '0') has_zero = true;
        else has_one = true;
        if (has_zero && has_one) break;
    }
    if (has_zero && has_one) return 'F';
    else if (has_zero) return 'B';
    else return 'I';
}

FBI_Node* build_tree(const string& s) {
    char type = determine_type(s);
    FBI_Node* node = new FBI_Node(type);
    if (s.length() > 1) {
        int mid = s.length() / 2;
        string left_str = s.substr(0, mid);
        string right_str = s.substr(mid);
        node->left = build_tree(left_str);
        node->right = build_tree(right_str);
    }
    return node;
}

void postorder(FBI_Node* node, string& result) {
    if (node == nullptr) return;
    postorder(node->left, result);
    postorder(node->right, result);
    result += node->type;
}

int main() {
    int N;
    string S;
    cin >> N >> S;
    FBI_Node* root = build_tree(S);
    string result;
    postorder(root, result);
    cout << result << endl;
    return 0;
}

看我看我，我宣布个事，我是个链接！