Cod sursa(job #3192746)

Utilizator hutanuHutanu Andrei hutanu Data 13 ianuarie 2024 10:55:26
Problema Algoritmul lui Dijkstra Scor 90
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.74 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, cmin[NMAX];

vector <pair<int, int>> G[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, k;
    pair <int,int> vf;
    fin >> n >> m;
    for(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(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<< ' ';
}