Cod sursa(job #638850)
#include <fstream>
#include <cstdlib>
#define N 3000010
using namespace std;
int A[N];
int n, k;
ifstream fin ("sdo.in");
ofstream fout ("sdo.out");
int swap(int i, int j) {
int aux = A[i];
A[i] = A[j];
A[j] = aux;
}
int partition(int p, int q) {
int x = rand() % (q - p + 1);
swap(p, x + p);
int i = p + 1;
for(int j = p + 1; j <= q; j++) {
if(A[j] <= A[p]) {
swap(j, i);
i++;
}
}
swap(i - 1, p);
return i - 1;
}
int computeKthMin(int nth, int l, int r) {
int u = partition(l, r);
if(u - l + 1 == nth) {
return A[u];
}
if((u - l + 1) < nth)
return computeKthMin(nth - (u - l + 1), u + 1, r);
else
return computeKthMin(nth, l, u - 1);
}
int main() {
freopen("sdo.in","r",stdin);
freopen("sdo.out","w",stdout);
fin >> n >> k;
for(int i = 1; i <= n; i++)
fin >> A[i];
fout << computeKthMin(k, 1, n);
return 0;
}