求用list怎么解

#include <iostream>
#include <list>
#include <iterator>
using namespace std;
int main() {
    freopen("apple.in", "r",stdin);
    freopen("apple.out", "w", stdout);
    int n;
    cin >> n;
    list<int> b;
    for (int i = 1; i <= n; i++) {
        b.push_back(i);
    }
    int d = 0;
    int db = 0;
    bool flag = false;
    while (!b.empty()) {
        ++d;
        list<int> bb;
        int x = 1;
        for (auto it = b.begin(); it != b.end(); ) {
            if (x % 3 == 1) {
                if (*it == n) {
                    db = d;
                    flag = true;
                }
                it = b.erase(it);
            } else {
                bb.push_back(*it);
                ++it;
            }
            ++x;
        }
        b = bb;
    }
    cout << d << " " << db << endl;
    fclose(stdin);
    fclose(stdout);
    
    
    return 0;
}