Cod sursa(job #3210959)

Utilizator rapidu36Victor Manz rapidu36 Data 7 martie 2024 19:49:15
Problema Statistici de ordine Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.25 kb
#include <fstream>
#include <cstdlib>

using namespace std;

const int N = 3e6;

int v[N];

void part3(int v[], int st, int dr, int &p1, int &p2)
{
    int i = st;
    p1 = st;
    p2 = dr - 1;
    while (i <= p2)
    {
        if (v[i] < v[dr])
        {
            swap(v[i++], v[p1++]);
        }
        else if (v[i] > v[dr])
        {
            swap(v[i], v[p2--]);
        }
        else///v[i]==v[dr]
        {
            i++;
        }
    }
    swap(v[++p2], v[dr]);
}

void qs(int v[], int st, int dr, int k)
{
    if (st >= dr)
    {
        return;
    }
    int p1, p2;
    part3(v, st, dr, p1, p2);
    if (k <= p1)
    {
        qs(v, st, p1 - 1, k);
    }
    if (k >= p2 + 1)
    {
        qs(v, p2 + 1, dr, k);
    }
}

void shuffle(int v[], int n)
{
    for (int i = n - 1; i > 0; i--)
    {
        int p = rand() % (i + 1);///poz. oarecare intre 0 si i inclusiv
        swap(v[i], v[p]);
    }
}

int main()
{
    ifstream in("sdo.in");
    ofstream out("sdo.out");
    int n, k;
    in >> n >> k;
    k--;
    for (int i = 0; i < n; i++)
    {
        in >> v[i];
    }
    shuffle(v, n);
    qs(v, 0, n - 1, k);
    out << v[k];
    in.close();
    out.close();
    return 0;
}