Cod sursa(job #862484)

Utilizator MonicaVizitiuMonica Vizitiu MonicaVizitiu Data 22 ianuarie 2013 18:45:25
Problema Algoritmul Bellman-Ford Scor 15
Compilator cpp Status done
Runda Arhiva educationala Marime 2.21 kb
#include <fstream>
#define INF 1000000000
using namespace std;

ifstream fin("bellmanford.in");
ofstream fout("bellmanford.out");

int n, start;
int cmin[6000], c[6000][6000];
int coada[6000], prim, ultim;
//int tata[5010];

void citire();
void afisare();
int bellman_ford(int start);
void drum(int x);
void bell();

int main()
{
    citire();
    bell();
    return 0;
}

void citire()
{
    int i, m, x, y, cost, j;
    fin>>n>>m; start=1;
    for(i=1;i<=n;i++)
        for(j=1;j<=n;j++)
            if(i!=j)
                c[i][j]=INF;
    for(i=1;i<=m;i++)
    {
        fin>>x>>y>>cost;
        c[x][y]=cost;
    }
}

/*void afisare()
{
    int i, x;
    x=bellman_ford(start);
    if(x==1) fout<<"Nu exista drum minim"<<'\n';
    else
        for(i=1;i<=n;i++)
        {
            fout<<"Costul pana la vf "<<i<<" este:"<<cmin[i]<<" iar drumul este: ";
            drum(tata[i]);
            fout<<i<<'\n';
        }
}*/

/*void afisare()
{
    int i, x;
    x=bellman_ford(start);
    if(x==1) fout<<"Ciclu negativ!"<<'\n';
    else
        for(i=2;i<=n;i++)
            fout<<cmin[i]<<' ';
}*/

/*void drum(int x)
{
    if(x==0) return;
    drum(tata[x]);
    fout<<x<<' ';
}*/

/*int bellman_ford(int start)
{
    int i, j, x, schimb;
    for(i=1;i<=n;i++)
        cmin[i]=INF;
    cmin[start]=0;
    for(i=1;i<=n;i++)
    {
        schimb=0;
        for(j=1;j<=n;j++)
            for(x=1;x<=n;x++)
            if (cmin[j]!=INF&&c[j][x]!=INF)
               if(cmin[x]>cmin[j]+c[j][x])
               {
                  cmin[x]=cmin[j]+c[j][x];
                  tata[x]=j; schimb=1;
               }
   }
   return schimb;
}*/

void bell()
{
    int i, x , ok, nr;
    int prim,ultim;
    for(i=1;i<=n;i++)
        cmin[i]=INF;
    cmin[start]=0;
	ultim=1; prim=1;
	coada[1]=start; x=start;
	while(prim<=ultim)
	{
		x=coada[prim++]; ok=0;
		for(i=1;i<=n;i++)
		{
			nr++;
			if(cmin[i]>cmin[x]+c[x][i]&&c[x][i]!=INF)
			{
			    coada[++ultim]=i;
                cmin[i]=cmin[x]+c[x][i]; ok=1;
            }
        }
	}
	if(ok) fout<<"Ciclu negativ!"<<'\n';
	else
        for(i=2;i<=n;i++)
            fout<<cmin[i]<<" ";
}