Cod sursa(job #2139170)

Utilizator radurotaruRotaru Radu Stefan radurotaru Data 22 februarie 2018 10:45:20
Problema Statistici de ordine Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 0.93 kb
#include <fstream>
#include <cstdlib>
#include <climits>
using namespace std;
ifstream f("sdo.in");
ofstream g("sdo.out");
int v[3000001],k,n;
void swap(int *a,int *b)
{
    int t=*a;
    *a=*b;
    *b=t;
}
int partition(int v[],int q,int w)
{
    int x=v[w];
    int i=q;
    for(int j=q; j<=w-1; j++)
    {
        if(v[j]<=x)
        {
            swap(v[i],v[j]);
            i++;
        }
    }
    swap(v[i],v[w]);
    return i;
}
int randompartition(int v[],int q,int w)
{
    int n=w-q+1;
    int pivot=rand()%n;
    swap(v[q+pivot],v[w]);
    return partition (v,q,w);
}
int kth(int v[],int q,int w,int k)
{
    int pos=randompartition(v,q,w);
    if(pos-q==k-1)
        return v[pos];
    if(pos-q>k-1)
        return kth(v,q,pos-1,k);
    return kth(v,pos+1,w,k-pos+q-1);

}
int main()
{
    f>>n>>k;
    for(int i=0; i<=n-1; i++)
        f>>v[i];
    g<<kth(v,0,n-1,k);
    return 0;
}