Cod sursa(job #1238643)

Utilizator romircea2010FMI Trifan Mircea Mihai romircea2010 Data 7 octombrie 2014 13:54:08
Problema Sortare prin comparare Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 2.16 kb
#include <iostream>
#include <fstream>
#include <cstdlib>
#include <ctime>

using namespace std;

const int NMax = 500010;
int n;
int a[NMax], aux[NMax];

void Read()
{
    ifstream f ("algsort.in");
    f >> n;
    for (int i = 1; i <= n; ++ i)
        f >> a[i];
    f.close();
}

inline int GetPoz(const int st, const int dr)
{
    int poz1 = st + (rand() % (dr - st + 1));
    int poz2 = st + (rand() % (dr - st + 1));
    int poz3 = st + (rand() % (dr - st + 1));
    if (a[poz1] <= a[poz2] && a[poz1] <= a[poz3])
    {
        if (a[poz2] <= a[poz3])
            return poz2;
        return poz3;
    }
    if (a[poz2] <= a[poz1] && a[poz2] <= a[poz3])
    {
        if (a[poz1] <= a[poz3])
            return poz1;
        return poz3;
    }
    if (a[poz1] <= a[poz2])
        return poz1;
    return poz2;
}

inline void QuickSort(const int st, const int dr)
{
    if (dr - st < 1)
        return ;
    if (dr - st == 1)
    {
        if (a[st] > a[dr])
            swap(a[st], a[dr]);
        return ;
    }
    int poz = GetPoz(st, dr);
    //int poz = (st+dr)/2;
    int pivot = a[poz];
    int l = st, r = dr;
    while (l <= r)
    {
        while (a[l] < pivot)
            ++ l;
        while (a[r] > pivot)
            -- r;
        if (l <= r)
        {
            swap(a[l], a[r]);
            ++l, --r;
        }
    }

    QuickSort(st, l-1);
    QuickSort(l, dr);

//    int count = 0;
//    for (int i = st; i <= dr; ++ i)
//    {
//        if (a[i] < pivot)
//        {
//            aux[l++] = a[i];
//            continue;
//        }
//        if (a[i] > pivot)
//        {
//            aux[r--] = a[i];
//            continue;
//        }
//    }
//    for (int i = l; i <= r; ++ i)
//        aux[i] = pivot;
//    for (int i = st; i <= dr; ++ i)
//        a[i] = aux[i];
//
//    QuickSort(st, l-1);
//    QuickSort(r+1, dr);
}

void Write()
{
    ofstream g ("algsort.out");
    for (int i = 1; i <= n; ++ i)
        g << a[i] << " ";
    g << "\n";
    g.close();
}

int main()
{
    srand(time(NULL));
    Read();
    QuickSort(1, n);
    Write();
    return 0;
}