Cod sursa(job #3192745)

Utilizator Alexia_CiobanuAlexia Maria Ciobanu Alexia_Ciobanu Data 13 ianuarie 2024 10:53:11
Problema Algoritmul lui Dijkstra Scor 90
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.67 kb
#include <fstream>
#include <vector>
#include <queue>
#define NMAX 50002
#define INF 1000000002

using namespace std;

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

int n, p=1,m;
 vector<pair<int,int>> G[NMAX];
int cmin[NMAX];
class ComparVf
{
public:
    bool operator() (int x,int y)
    {
        return cmin[x]>cmin[y];
    }
};
priority_queue<int, vector<int>, ComparVf>H;
void citire();
void dijkstra();
void afisare();

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

void citire()
{
    int i, j, c;
    pair<int,int> vf;
    fin >> n>>m;
    for(int k=0;k<m;k++)
    {
        fin>>i>>j>>c;
        vf.first=j;
        vf.second=c;
        G[i].push_back(vf);
    }
}

void dijkstra()
{
    int i, x, vfmin, c;
    ///initializare
    H.push(p);
    for(int i=1;i<=n;i++)
        cmin[i]=INF;
    cmin[p]=0;
    ///dijkstra
    while(!H.empty())
    {
        ///determin minimul din cmin pentru varfurile x pt care uz[x] = 0
        vfmin=H.top();
        H.pop();
        if(cmin[vfmin] == INF) break;
        ///optimizez eventual costurile catre celelalte varfuri, trecand prin vfmin
        ///parcurg lista de adiacenta a lui vf min
        for(i=0;i<G[vfmin].size();i++)
        {
            x=G[vfmin].at(i).first; c=G[vfmin].at(i).second;
            if( cmin[x] > cmin[vfmin] + c)
            {
                cmin[x] = cmin[vfmin] + c;
                H.push(x);
            }
        }
    }
}

void afisare()
{
    int i;
    for(i = 2; i <= n; i++)
        if(cmin[i] != INF)
            fout << cmin[i] <<' ';
        else
            fout <<0<< ' ';
}