Cod sursa(job #2606830)

Utilizator toadehuPuscasu Razvan Stefan toadehu Data 28 aprilie 2020 18:30:41
Problema Statistici de ordine Scor 0
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1 kb
#include <bits/stdc++.h>

using namespace std;

const int Nmax=3000009;

int v[Nmax], n, k;

int part (int v[Nmax], int li, int lf)
{
    int i=li-1,j=lf+1,p=v[li+(rand()%(lf-li+1))];
    while (true)
    {
        while (v[i] < p)
        {
            ++i;
        }
        while (p < v[j])
        {
            --j;
        }
        if (i < j)
        {
            swap (v[i], v[j]);
        }
        else
        {
            return j;
        }
    }

    return 0;
}

void quick (int v[Nmax], int li, int lf, int k)
{
    if (li==lf)
    {
        return;
    }
    int q=part(v, li, lf);
    int t=q-li+1;
    if (t>=k)
    {
        quick (v, li, q, k);
    }
    else
    {
        quick (v, q+1, lf, k-t);
    }
}

int main()
{
    ios::sync_with_stdio(0);
    ifstream fin ("sdo.in");
    ofstream fout ("sdo.out");
    fin>>n>>k;
    for(int i=1; i<=n; ++i)
    {
        fin>>v[i];
    }
    quick(v, 1, n, k);
    fout<<v[k]<<"\n";
}