Cod sursa(job #695300)

Utilizator Teodor94Teodor Plop Teodor94 Data 28 februarie 2012 11:44:15
Problema Statistici de ordine Scor 90
Compilator cpp Status done
Runda Arhiva educationala Marime 1.04 kb
#include <fstream>
#include <ctime>
#include <cstdlib>
#include<algorithm>

using namespace std;

ifstream in ("sdo.in");
ofstream out ("sdo.out");

const int N = 3000005;

int a[N], n, k;

void citire() {
	in >> n >> k;

	for (int i = 1; i <= n; ++i)
        in >> a[i];
}

int prelucrare(int a[], int left, int right) {
	int st = left, dr = right, pivot = a[left + (rand() % (right - left + 1) )];

	while(true) {
		while (a[st] < pivot)
            ++st;

        while (a[dr] > pivot)
            --dr;

		if (st < dr)
			swap(a[st], a[dr]);
		else
			return dr;
	}

	return 0;
}

void quicksort(int a[], int left, int right, int k) {
	if(left == right)
		return;

	int poz = prelucrare(a, left, right);
	int p = poz - left + 1;

	if (p >= k)
		quicksort(a, left, poz, k);
	else
		quicksort(a, poz + 1, right, k - p);
}

int main() {
    freopen("sdo.in", "r", stdin);
    freopen("sdo.out", "w", stdout);

	srand(time(0));

	citire();

	quicksort(a, 1, n, k);

	out << a[k];

	return 0;
}