Cod sursa(job #544437)

Utilizator BitOneSAlexandru BitOne Data 1 martie 2011 16:38:24
Problema Algoritmul lui Dijkstra Scor 70
Compilator cpp Status done
Runda Arhiva educationala Marime 1.75 kb
#include <vector>
#include <fstream>
#include <cstdlib>
#define N_MAX 50011
#define oo 1<<20
#define pr pair< int, int >
#define mkpr make_pair< int, int >

using namespace std;
int N;
vector< pr > G[N_MAX];
vector< pr >::const_iterator it, iend;
bool isIn[N_MAX];
int H[N_MAX], P[N_MAX], d[N_MAX];
inline void _swap( int& x, int& y ) { int aux=x; x=y; y=aux; }
inline int _min( int x, int y ) { return ( x <= y ? x : y ); }
inline int _max( int x, int y ) { return ( x >= y ? x : y ); }
void DownHeap( int k )
{
	for( int son=2*k; son <= N; son*=2 )
	{
		if( son < N && d[H[son]] > d[H[son+1]] )
			++son;
		if( H[k] <= H[son] )
			return;
		_swap( H[k], H[son] );
		P[H[k]]=k;
		P[H[son]]=son;
	}
}
inline void UpHeap( int k )
{
	for( int key=d[H[k]], f=k/2; k > 1 && d[H[f]] > key; k=f, f/=2 )
	{
		_swap( H[k], H[f] );
		P[H[k]]=k;
		P[H[f]]=f;
	}
}
inline int pop()
{
	int r=H[1];
	P[H[N]]=1;
	H[1]=H[N];
	--N;
	DownHeap( 1 );
	return r;
}
inline void push( int k, int dis )
{
	d[k]=dis;
	H[++N]=k;
	P[k]=N;
	UpHeap( N );
}
int main( void )
{
	int n, M, x, y, c;
	ifstream in( "dijkstra.in" );
	for( in>>n>>M; M; --M )
	{
		in>>x>>y>>c;
		G[x].push_back( mkpr( y, c ) );
	}
	for( x=1; x <= n; ++x )
		d[x]=oo;
	for( push( 1, 0 ); N; )
	{
		x=pop();
		isIn[x]=false;
		for( it=G[x].begin(), iend=G[x].end(); it < iend; ++it )
		{
			if( d[it->first] > d[x]+it->second )
			{
				d[it->first]=d[x]+it->second;
				if( false == isIn[it->first] )
				{
					push( it->first, d[x]+it->second );
					isIn[it->first]=true;
				}
				else UpHeap( P[it->first] );
			 }
		}
	}
	ofstream out( "dijkstra.out" );
	for( x=2; x <= n; ++x )
		out<<( oo == d[x] ? 0 : d[x] )<<' ';
	out<<'\n';
	return EXIT_SUCCESS;
}