Heap sort

#include <bits/stdc++.h>

using namespace std;

ifstream f("date.in");
ofstream g("date.out");

struct node{
    int inf;
    node *urm, *ant;
};

node *prim, *ultim;

void creare(int x){
    prim = new node;
    prim -> inf = x;
    prim -> urm = NULL;
    prim -> ant = NULL;
    ultim = prim;
}

void afisare(){
    node *p = prim;
    while(p != NULL){
        g << p -> inf << " ";
        p = p -> urm;
    }
}

void inseraref(int x){
    node *p = new node;
    p -> inf = x;
    p -> ant = NULL;
    p -> urm = prim;
    prim = p;
}

void inserareb(int x){
    node *p = new node;
    p -> inf = x;
    p -> ant = ultim;
    p -> urm = NULL;
    ultim -> urm = p;
    ultim = p;
}

void inserare(int x){
    node *p = prim;
    while(p != NULL){
        if(p -> inf <= x && p -> urm -> inf >= x){
            node *t = new node;
            t -> inf = x;
            t -> ant = p;
            t -> urm = p -> urm;
            p -> urm = t;
            break;
        }
        p = p -> urm;
    }
}

int main(){
    int x;
    f >> x;
    creare(x);

    while(f >> x){
        if(x < prim -> inf)
            inseraref(x);
        else
            if(x > ultim -> inf)
                inserareb(x);
            else
                inserare(x);
    }

    afisare();
    return 0;
}