Cod sursa(job #800588)

Utilizator igsifvevc avb igsi Data 22 octombrie 2012 04:05:05
Problema Sortare prin comparare Scor 60
Compilator cpp Status done
Runda Arhiva educationala Marime 1.19 kb
#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;
}