Cod sursa(job #1535030)

Utilizator Eman98Ghinea Mihail Emanuel Eman98 Data 24 noiembrie 2015 11:28:16
Problema Algoritmul lui Dijkstra Scor 20
Compilator cpp Status done
Runda Arhiva educationala Marime 1.7 kb
#include<fstream>
#include<vector>
#include<climits>
#define N 50002
#define inf INT_MAX
using namespace std;
ifstream cin("dijkstra.in");
ofstream cout("dijkstra.out");
vector <pair <int,int> > G[N];
int m,n,a,b,c,i,drum[N],dim=1,H[N],poz[N],nod,j,x;
void up(int nod)
{
    while(!nod/2 and drum[H[nod/2]]>drum[H[nod]])
    {
        swap(H[nod/2],H[nod]);
        swap(poz[H[nod/2]],poz[H[nod]]);
        nod/=2;
    }
}
void down()
{
    int nod=1;
    while(2*nod<dim)
    {
        int aux=2*nod;
        if(aux+1<dim and drum[H[aux+1]]<drum[H[aux]])
            aux++;
        if(drum[H[aux]]<drum[H[nod]])
        {
            swap(H[aux],H[nod]);
            swap(poz[H[aux]],poz[H[nod]]);
            nod=aux;
        }
        else
            break;
    }
}
int main()
{
    cin>>n>>m;
    for(i=1;i<=m;i++)
    {
        cin>>a>>b>>c;
        G[a].push_back(make_pair(b,c));
    }
    for(i=2;i<=n;i++)
        drum[i]=inf;
    H[1]=1;
    poz[1]=1;
    for(i=1;i<=n;i++)
    {
        nod=H[1];
        H[1]=H[dim];
        poz[H[1]]=1;
        dim--;
        down();
        for(j=0;j<(int)G[nod].size();j++)
        {
            x=G[nod][j].first;
            c=G[nod][j].second;
            if(drum[x]>drum[nod]+c)
            {
                drum[x]=drum[nod]+c;
                if(!poz[x])
                {
                    H[++dim]=x;
                    poz[x]=dim;
                    up(dim);
                }
                else
                    up(poz[x]);
            }
        }
    }
    for(i=2;i<=n;i++)
        if(drum[i]!=inf)
            cout<<drum[i]<<" ";
        else
            cout<<0<<" ";
    return 0;
}