Cod sursa(job #2162461)

Utilizator cella.florescuCella Florescu cella.florescu Data 12 martie 2018 11:15:38
Problema Statistici de ordine Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 0.77 kb
#include <bits/stdc++.h>

using namespace std;

const int MAXN = 3e6;

int v[MAXN];

int part(int l, int r) {
  int piv = v[l + rand() % (r - l + 1)];
  while (l <= r) {
    while (piv > v[l])
      ++l;
    while (piv < v[r])
      --r;
    if (l <= r)
      swap(v[l++], v[r--]);
  }
  return r;
}

void compute(int l, int r, int k) {
  if (l < r) {
    int p = part(l, r);
    if (k <= p - l)
      compute(l, p, k);
    else
      compute(p + 1, r, k - p + l - 1);
  }
}

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