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Cod sursa(job #800588)
#include <fstream>
#include <cstdlib>
using namespace std;
ifstream fin("algsort.in");
ofstream fout("algsort.out");
int v[500001], n;
int m, a, b, c; /* variables for finding the median of 3 */
void quicksort(int l, int r)
{
if(l < r)
{
/* finding the pivot element and partitionig around it */
int i, j, aux;
/* pick the median of 3 */
a = l + rand() % (r-l+1);
b = l + rand() % (r-l+1);
c = l + rand() % (r-l+1);
if( (v[a] <= v[b] && v[b] <= v[c]) || (v[c] <= v[b] && v[b] <= v[a]) ) m = b;
else if( (v[b] <= v[a] && v[a] <= v[c]) || (v[c] <= v[a] && v[a] <= v[b]) ) m = a;
else if( (v[a] <= v[c] && v[c] <= v[b]) || (v[b] <= v[c] && v[c] <= v[a]) ) m = c;
aux = v[m]; v[m] = v[r]; v[r] = aux;
/* partition */
for(i = l-1, j = l; j <= r-1; j++)
if(v[j] <= v[r])
{
aux = v[++i];
v[i] = v[j];
v[j] = aux;
}
aux = v[++i];
v[i] = v[r];
v[r] = aux;
/* finished partitioning */
quicksort(l, i-1);
quicksort(i+1, r);
}
}
int main()
{
int i;
srand(16);
fin >> n;
for(i = 1; i <= n; ++i)
fin >> v[i];
quicksort(1, n);
for(i = 1; i <= n; ++i)
fout << v[i] << ' ';
fout << endl;
fin.close();
fout.close();
return 0;
}