Cod sursa(job #588438)

Utilizator BlaugranasEnal Gemaledin Blaugranas Data 7 mai 2011 23:28:44
Problema Statistici de ordine Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.06 kb
#include<fstream.h>
#define N 3000001
long n,a[N],i,k,j=0,t=0;
long partition(long a[N],long p,long r)
{long i=p-1,j,x=a[r],m;
for(j=p;j<r;j++)
if(a[j]<=x)
      {i++;
      if(i!=j&&a[i]!=a[j])
            m=a[i],a[i]=a[j],a[j]=m;}
if(i+1!=r&&a[i+1]!=a[r])
      m=a[i+1],a[i+1]=a[r],a[r]=m;
return i+1;}

long randomized_partition(long a[N],long p,long r)
{long m;
if((p+r)%2==0)
      m=a[r],a[r]=a[p],a[p]=m;
return partition(a,p,r);}

long select(long a[N],long p,long r,long i)
{long q,k;
if(p==r)
      return a[p];
q=randomized_partition(a,p,r);
k=q-p+1;
if(i==k)
      return a[q];
else
      if(i<k)
             return select(a,p,q-1,i);
      else
             return select(a,q+1,r,i-k);}
int main()
{ifstream f("sdo.in");
ofstream g("sdo.out");
f>>n>>k>>a[1];
for(i=2;i<=n;i++)
      {f>>a[i];
      if(a[i-1]<a[i])
             j++;
      else
             t++;}
if(j==n-1)
      g<<a[k];
else
      if(t==n-1)
             g<<a[n-k+1];
      else
             g<<select(a,1,n,k);
f.close();
g.close();
return 0;}