Cod sursa(job #3192739)

Utilizator Frant_IoanaFrant Ioana Frant_Ioana Data 13 ianuarie 2024 10:52:28
Problema Algoritmul lui Dijkstra Scor 90
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.77 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;
vector<pair<int, int> > G[NMAX]; //varf si cost
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, m;
    pair<int, int> vf;
    fin >> n >> m;
    for(int k = 0; k < m; k++)
    {
        fin >> i >> j >> c;
        //am arc de la i la j de cost c
        //in lista de adiacenta a lui i trebuie sa punem varful j si costul j
        vf.first = j;
        vf.second = c;
        G[i].push_back(vf);
    }
}

void dijkstra()
{
    int i, x, vfmin, minim;
    //initializare
    H.push(p);
    for(i = 1; i <= n; i++)
        cmin[i] = INF;
    cmin[p] = 0;

    while(!H.empty())
    {
        vfmin = H.top();
        H.pop();
        if(cmin[vfmin] == INF) break;
        //vfmin este selectat
        //optimizez costurile catre celelalte varfuri, trecand prin vfmin
        //parcurg lista de adiacenta a lui vfmin
        int idk = G[vfmin].size();
        for(i = 0; i < idk; i++){
            x = G[vfmin][i].first;
            int c = G[vfmin][i].second;
            if(cmin[x] > cmin[vfmin] + c){
                cmin[x] = cmin[vfmin] + c;
                H.push(x);
            }
        }
    }
}

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