Cod sursa(job #431578)

Utilizator AndreyPAndrei Poenaru AndreyP Data 1 aprilie 2010 10:21:02
Problema Statistici de ordine Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 0.78 kb
#include<cstdio>
#include<cstdlib>
#include<ctime>
#include<fstream>
using namespace std;
#define N 3000010
ifstream in("sdo.in");
ofstream out("sdo.out");
int n,k;
int a[N];
inline void citire()
{
	in>>n>>k;
	for(int i=1; i<=n; ++i)
		in>>a[i];
}
inline int part(int p,int u)
{
	int piv=a[p+rand()%(u-p+1)];
	int i=p-1,j=u+1;
	
	while(true)
	{
		++i;
		--j;	
		while(a[i]<piv)
			++i;
		while(piv<a[j])
			--j;
		if(i<j)
			swap(a[i],a[j]);
		else
			return j;
	}
	return j;
}
void rezolva(int p,int u)
{
	if(p>=u)
		return;
	int poz=part(p,u);
	
	if(poz-p+1>=k)
		rezolva(p,poz);
	else
	{
		k-=poz-p+1;
		rezolva(poz+1,u);
	}
}
int main()
{	
	citire();
	srand(time(NULL));
	int k1=k;
	rezolva(1,n);
	out<<a[k1]<<'\n';
	
	return 0;
}