Cod sursa(job #3349282)

Utilizator rapidu36Victor Manz rapidu36 Data 27 martie 2026 11:03:59
Problema Statistici de ordine Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.08 kb
#include <fstream>
#include <cstdlib>

using namespace std;

const int N = 3e6;

int v[N], aux[N];

void part_3(int v[], int st, int dr, int &p1, int &p2) {
    ///alegem pivotul la intamplare
    int p_piv = st + rand() % (dr - st + 1);
    swap(v[p_piv], v[dr]);
    int i = st;
    p1 = st;
    p2 = dr - 1;
    while (i <= p2) {
        if (v[i] < v[dr]) {
            swap(v[p1++], v[i++]);
        } else if (v[i] == v[dr]) {
            i++;
        } else { // v[i] > v[dr]
            swap(v[p2--], v[i]);
        }
    }
    swap(v[++p2], v[dr]);
}

void quick_sort(int v[], int st, int dr, int k)
{
    if (st >= dr)
    {
        return;
    }
    int p1, p2;
    part_3(v, st, dr, p1, p2);
    if (k < p1) {
        quick_sort(v, st, p1 - 1, k);
    }
    if (k > p2) {
        quick_sort(v, p2 + 1, dr, k);
    }
}

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