Cod sursa(job #1267683)

Utilizator MihaiStanMihail Stan MihaiStan Data 20 noiembrie 2014 08:50:00
Problema Algoritmul lui Dijkstra Scor 50
Compilator cpp Status done
Runda Arhiva educationala Marime 1.79 kb
#include <fstream>
#include <cstdio>
#include <vector>
#define NMAX 50001
#define INF 1000000000

using namespace std;

FILE * fin=fopen("dijkstra.in", "r");
FILE * fout=fopen("dijkstra.out", "w");

struct vecin
{
    int vf;
    short int c;
};

vector <vecin> g[NMAX];
int n,x0=1;
int cmin[NMAX],prec[NMAX];
bool z[NMAX];

void citire_init();
void dijkstra();
void afisare();

int main()
{
    citire_init();
    dijkstra();
    afisare();
    return 0;
}

void citire_init()
{
    int i,m,x,y,c;
    vecin aux;
    fscanf(fin,"%d%d",&n,&m);
    for(i=0;i<m;i++)
    {
        fscanf(fin, "%d %d %d", &x, &y, &c);
        aux.vf=y;
        aux.c=c;
        g[x].push_back(aux);
    }

    z[x0]=1;
    for(i=1;i<=n;i++)
    {
        prec[i]=x0;
        cmin[i]=INF;
    }
    prec[x0]=0;
    cmin[x0]=0;

    for(i=0;i<g[x0].size();i++)
        cmin[g[x0][i].vf]=g[x0][i].c;
}

void dijkstra()
{
    int i,j,vfmin,costminim=0;
    for(i=1;i<=n-1;i++)
    {
        //determin vf neselectat de cost minim
        costminim=INF;
        for (j=1;j<=n;j++)
            if(cmin[j]<costminim && z[j]==0)
            {
                vfmin=j;
                costminim=cmin[j];
            }
        if(costminim==INF) break;
        //selectez
        z[vfmin]=1;
        //parcurg lista de adiacenta a lui vfmin
        for (j=0;j<g[vfmin].size();j++)
            if(cmin[g[vfmin][j].vf]>cmin[vfmin]+g[vfmin][j].c)
            {
                cmin[g[vfmin][j].vf]=cmin[vfmin]+g[vfmin][j].c;
                prec[g[vfmin][j].vf]=vfmin;
            }
    }

}

void afisare()
{
    int i;
    for(i=2;i<=n;i++)
        if(cmin[i]==INF)
            fprintf(fout,"0 ");
            else
                fprintf(fout,"%d ",cmin[i]);
}