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Cod sursa(job #373224)
#include<fstream>
#include<algorithm>
#include<ctime>
#include<cstdlib>
using namespace std;
const int Max=3000003;
int a[Max];
int n,k;
ifstream fin ("sdo.in");
ofstream fout ("sdo.out");
int partition(int a[Max],int st,int dr)
{
int i=st-1,j=dr+1,q=a[st+(rand()%(dr-st+1))];
while(1)
{
do
{
i++;
}while(a[i]<q);
do
{
j--;
}while(q<a[j]);
if(i<j)
swap(a[i],a[j]);
else
return j;
}
return 0;
}
inline void sdo(int a[Max],int st,int dr,int ind)
{
if(st==dr)
return ;
int q=partition(a,st,dr);
int k=q-st+1;
if(ind<=k)
sdo(a,st,q,ind);
else
sdo(a,q+1,dr,ind-k);
}
int main()
{
srand(time(NULL));
fin>>n>>k;
for(int i=1;i<=n;i++)
{
fin>>a[i];
}
sdo(a,1,n,k);
fout<<a[k]<<'\n';
return 0;
}