Cod sursa(job #2401079)

Utilizator CameliaSSamoilescu Camelia CameliaS Data 9 aprilie 2019 13:34:09
Problema Algoritmul lui Dijkstra Scor 30
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.67 kb
#include <iostream>
#include <queue>
#include <vector>
#include <fstream>
using namespace std;


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

#define inf 20005
#define NMAX 50000

vector< int > graph[NMAX], graphC[NMAX];
priority_queue <pair <int, int> > myheap;



int n, m, dist[NMAX], viz[NMAX];

void citire(){
    f>>n>>m;

    for(int i = 0; i < m; i ++)
    {
        int a, b, c;
        f>>a>>b>>c;
        /// muchie de la a->b
        graph[a].push_back(b);

        /// costul muchiei de la a->b
        graphC[a].push_back(c);
    }

}



void algoritm(){

    int index;
    for(int i = 1; i <= n; i ++)
        dist[i] = inf;
    int sursa = 1;
    dist[sursa] = 0;

    myheap.push(make_pair(0, sursa));
    for(int i = 2; i <= n; i ++)
        myheap.push(make_pair(inf, i));


    while(!myheap.empty())
    {
        pair<int, int> best = myheap.top();
        index = best.second;
        int nrVecini = graph[index].size();

        viz[index] = 1;

        /// parcurg vecinii nodului index;
        for(int j = 0; j < nrVecini; j ++)
        {
            int vecin = graph[index][j];
            int cost = graphC[index][j];
            if((dist[index] + cost) < dist[vecin])
                {
                    dist[vecin] = dist[index] + cost;
                    myheap.push(make_pair(-dist[vecin], vecin));
                }
        }
        myheap.pop();

    }


}

void afisare(){
    for(int i = 2; i <= n; i ++)
        if(dist[i] == inf)
            g<<0<<" ";
        else g<<dist[i]<<" ";
}


int main()
{

    citire();
    algoritm();
    afisare();
    return 0;
}