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Cod sursa(job #379318)
/*
* File: main.cpp
* Author: virtualdemon
*
* Created on December 31, 2009, 4:23 PM
*/
#include <vector>
#include <fstream>
#include <iterator>
/*
*
*/
using namespace std;
vector<int> v;
int size_threshold;
ofstream out;
inline void swap( int x, int y )
{
v[x]+=v[y];
v[y]=v[x]-v[y];
v[x]-=v[y];
}
inline int medianof3( int left, int middle, int right )
{
if( v[left] > v[middle] )
swap( left, middle );
if( v[left] > v[right] )
swap( left, right );
if( v[middle] > v[right] )
swap( middle, right );
swap( middle, right-1 );
return v[right-1];
}
int Partition( int left, int right, int pValue )
{
int leftPtr=left, rightPtr=right;
while( true )
{
while( v[++leftPtr] < pValue );
while( v[--rightPtr] > pValue );
if( leftPtr >= rightPtr )
break;
swap( leftPtr, rightPtr );
}
swap( left, right-1 );
return leftPtr;
}
void QSort_Loop( int left, int right )
{
while( right-left > size_threshold )
{
int p=Partition( left, right, medianof3( left, left+(right-left)/2-1, right-1 ) );
if( p-left >= p-right )
{
QSort_Loop( p, right );
right=p-1;
}
else {
QSort_Loop( left, p );
left=p+1;
}
}
}
void Insertion_Sort( int left, int right )
{int key, j;
for( left+=1; left < right; ++left )
{
key=v[left];
for( j=left-1; j >=0 && v[j] > key; --j )
v[j+1]=v[j];
v[j+1]=key;
}
}
inline void QSort( int left, int right )
{
QSort_Loop( left, right );
Insertion_Sort( left, right );
}
int Log2( int n)
{
int pos = 0;
if (n >= 1<<16) { n >>= 16; pos += 16; }
if (n >= 1<< 8) { n >>= 8; pos += 8; }
if (n >= 1<< 4) { n >>= 4; pos += 4; }
if (n >= 1<< 2) { n >>= 2; pos += 2; }
if (n >= 1<< 1) { pos += 1; }
return ((n == 0) ? (-1) : pos);
}
int main()
{int n;
ifstream in("algsort.in");
in>>n;
copy( istream_iterator<int>(in), istream_iterator<int>(), back_inserter(v) );
out.open("algsort.out");
size_threshold=Log2(n);
QSort( 0, n );
copy( v.begin(), v.end(), ostream_iterator<int>(out, " ") );
return 0;
}