15 Однонаправленный список

#include <iostream>
#include <string>
#include <fstream>
#include <stack>
#include <queue>
#include <list>
#include <forward_list>

using namespace std;



ifstream in("input.txt");
ofstream out("output.txt");

// input.txt : 1 -5 2 3 -4 51 -14 -24 1 5

int main()
{
    forward_list<int> fl;
    while (in.peek() != EOF)
    {
        int cur; in >> cur;
        fl.push_front(cur);
    }
    forward_list<int> ans;
    forward_list<int> rev_temp;
    while (!fl.empty())
    {
        int cur = fl.front();
        fl.pop_front();
        if (cur < 0)
            ans.push_front(cur);
        else
            rev_temp.push_front(cur);
    }
    forward_list<int> temp;
    while (!rev_temp.empty())
    {
        int cur = rev_temp.front();
        rev_temp.pop_front();
        temp.push_front(cur);
    }

    while (!temp.empty())
    {
        int cur = temp.front();
        temp.pop_front();
        ans.push_front(cur);
    }
    for (auto v : ans)
        cout << v << " ";

}