Cod sursa(job #705622)

Utilizator BitOneSAlexandru BitOne Data 4 martie 2012 17:58:14
Problema Algoritmul lui Dijkstra Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.57 kb
#include <vector>
#include <fstream>
#include <cstdlib>
#define N_MAX 50011
#define oo 1<<29
#define pr pair< int, int >

using namespace std;

int lHeap;
int d[N_MAX], H[N_MAX], P[N_MAX];
vector< pr > G[N_MAX];
vector< pr >::const_iterator it, iend;

inline void _swap( int& x, int& y ) { int aux=x; x=y; y=aux; }
void DownHeap( int k )
{
	for( int son=k<<1; son <= lHeap; k=son, son<<=1 )
	{
		if( son < lHeap && d[H[son+1]] < d[H[son]] )
			++son;
		if( d[H[k]] <= d[H[son]] )
			return;
		_swap( H[k], H[son] );
		P[H[k]]=k;
		P[H[son]]=son;
	}
}
void UpHeap( int k )
{
	for( int key=d[H[k]], f=k>>1; k > 1 && key < d[H[f]]; k=f, f>>=1 )
	{
		_swap( H[k], H[f] );
		P[H[k]]=k;
		P[H[f]]=f;
	}
}
inline int pop()
{
	int r=H[1];
	
	P[H[1]]=-1;
	H[1]=H[lHeap];
	P[H[1]]=1;
	--lHeap;
	DownHeap( 1 );

	return r;
}
inline void push( int x )
{
	H[++lHeap]=x;
	P[x]=lHeap;
	UpHeap( lHeap );
}
int main()
{
	int N, M, x, y, c, i;
	ifstream in( "dijkstra.in" );
	ofstream out( "dijkstra.out" );
	
	for( in>>N>>M; M; --M )
	{
		in>>x>>y>>c;
		G[x].push_back( pr( y, c ) );
	}
	fill( d, d+N+1, oo );
	d[1]=0;
	for( push(1); lHeap;  )
	{
		x=pop();
		for( it=G[x].begin(), iend=G[x].end(); it < iend; ++it )
			if( oo == d[it->first] )
			{
				d[it->first]=d[x]+it->second;
				push( it->first );
			}
			else if( d[it->first] > d[x] + it->second )
				 {
					 d[it->first]=d[x]+it->second;
					 UpHeap( P[it->first] );
				 }
	}
	for( i=2; i <= N; ++i )
		out<<( oo == d[i] ? 0 : d[i] )<<' ';
	out<<'\n';
	return EXIT_SUCCESS;
}