Cod sursa(job #2353955)

Utilizator nurof3nCioc Alex-Andrei nurof3n Data 24 februarie 2019 19:07:38
Problema Algoritmul lui Dijkstra Scor 20
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.64 kb
//SHORTEST PATH FASTER ALGORITHM = DIJKSTRA CU COADA SIMPLA
//DETECTEAZA CIRCUITELE DE COST NEGATIV!!


#include <fstream>
#include <vector>

using namespace std;

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

const int MAX = 50001;

int Q[MAX * 4];
int st, dr;
vector<pair<int, int>> G[MAX];

int D[MAX];  //retine costul minim al drumului pana la fiecare nod, care trece doar prin nodurile vizitate
int N, M;
bool viz[MAX];  //vectorul caracteristic al multimii nodurilor pt care drumul de cost minim este deja calculat

void SPFA() {
    int i, vf, nod, cost, lg;
    while (st <= dr) {
        vf = Q[st++];
        if (viz[vf])
            continue;
        lg = G[vf].size();
        for (i = 0; i < lg; i++) {
            nod = G[vf][i].first;
            cost = G[vf][i].second;
            if (D[vf] + cost < D[nod]) {
                D[nod] = D[vf] + cost;
                if(!viz[nod])
                    Q[++dr] = nod;
            }
        }
        viz[vf] = true; //adaugam nodul vf la multimea nodurilor pt care am calculat deja drumul minim
    }
}

int main() {

    int x, y, cost;
    in >> N >> M;
    for (int i = 1; i <= N; i++)
        D[i] = 1000000;
    D[1] = 0;

    st = 1, dr = 0;
    for (int i = 1; i <= M; i++) {
        in >> x >> y >> cost;
        G[x].push_back (pair<int, int> (y, cost));
        if(x == 1) {
            D[y] = cost;
            Q[++dr] = y;
        }
    }

    viz[1] = true;
    SPFA();

    for (int i = 2; i <= N; i++)
        if (D[i] < 1000000)
            out << D[i] << ' ';
        else
            out << 0 << ' ';

    return 0;
}