Cod sursa(job #1003858)

Utilizator ThomasFMI Suditu Thomas Thomas Data 1 octombrie 2013 18:41:20
Problema Algoritmul lui Dijkstra Scor 0
Compilator cpp Status done
Runda Arhiva educationala Marime 2.67 kb
#include <fstream>
#include <algorithm>
#include <vector>
using namespace std;

#define Nmax 50001
#define pb push_back
#define inf 1001

ifstream f("dijkstra.in");
ofstream g("dijkstra.out");

int n,m,i,a,b,x,w;
int H[Nmax],h,poz[Nmax],d[Nmax];
vector<int> v[Nmax],c[Nmax];

void afis()
{
    g<<"d:    ";for(i=2;i<=n;i++) if(d[i]==inf) g<<"inf "; else g<<d[i]<<" "; g<<"\n";
    g<<"poz:  ";for(i=2;i<=n;i++) if(poz[i]==-1) g<<"0 "; else g<<poz[i]<<" "; g<<"\n";
    g<<"H:    ";for(i=1;i<=h;i++) g<<H[i]<<" "; g<<"\n";
    g<<"d[H]: ";for(i=1;i<=h;i++) g<<d[H[i]]<<" "; g<<"\n";
    g<<"\n";
}

void perc(int x)
{
    int xx;
    while(x>1)
    {
        xx=x/2;
        if (d[H[xx]]>d[H[x]])
        {
            poz[H[x]]=xx;
            poz[H[xx]]=x;
            swap(H[x],H[xx]);
            x=xx;
        }
        else x=1;
    }
}

void sift(int x)
{
    int son,xx,xy;
    while(x<=h)
    {
        xx=x*2;
        xy=xx+1;

        if (xx<=h)
        {
            son=xx;
            if(xy<=h)
                if(d[H[xy]]<d[H[xx]]) son=xy;
        }
        else return;

        if (d[H[x]]>d[H[son]])
        {
            poz[H[x]]=son;
            poz[H[son]]=x;
            swap(H[x],H[son]);
            x=son;
        }
        else return;
    }
}

void dijkstra_heap()
{
    //initializare
    int j,q;
    for(j=2;j<=n;j++) {d[j]=inf; poz[j]=-1;}
    poz[1]=1;
    H[++h]=1;

    while(h)
    {
        //eliminam minimul
        int minim=H[1];
        swap(H[1],H[h]);
        poz[H[1]]=1;
        --h;
        sift(1);

        w=v[minim].size();

        g<<"\n~~~~~~~~~~~~~\n";
        afis();
        g<<"---------------\n";

        for(q=0;q<w;q++)
        {

            /*g<<"d[v[minim][q]]=d["<<v[minim][q]<<"]="<<d[v[minim][q]]<<"\n";
            g<<"d[minim]=d["<<minim<<"]="<<d[minim]<<"\n";
            g<<"cost 1 -> "<<v[minim][q]<<" = "<<c[minim][q]<<"\n";g<<"\n";*/

            if ( d[v[minim][q]] > d[minim] + c[minim][q])
            {
                d[v[minim][q]] = d[minim] + c[minim][q];

                if (poz[v[minim][q]] != -1)
                    perc(poz[v[minim][q]]);
                else
                {
                    H[++h]=v[minim][q];
                    poz[H[h]]=h;
                    sift(h);
                }
            }
            afis();
        }
    }
}

int main()
{
    f>>n>>m;
    for(i=1;i<=m;i++)
    {
        f>>a>>b>>x;
        v[a].pb(b);
        c[a].pb(x);
    }

    dijkstra_heap();

    //for(i=2;i<=n;i++) if(d[i]==inf) g<<"0 "; else g<<d[i]<<" "; g<<"\n";

    f.close();
    g.close();
    return 0;
}