Cod sursa(job #1379557)

Utilizator oprea1si2si3Oprea Sebastian oprea1si2si3 Data 6 martie 2015 18:23:03
Problema Algoritmul Bellman-Ford Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.66 kb
#include <fstream>
#include <vector>
#include <queue>
using namespace std;

const int kNMax = 50010, Inf = 9999999;
int n, dist[kNMax], contor[kNMax], ok;
bool in_q[kNMax];
queue<int> Queue;
vector<pair<int,int> > G[kNMax];


void Citire() {
    ifstream in("bellmanford.in");
    int m, x, y, c;
    in >> n >> m;
    for (int i = 1; i <= m; ++i) {
        in >> x >> y >> c;
        G[x].push_back(make_pair(y, c));
    }
    in.close();
}

void Initializare() {
    for (int i = 1; i <= n; ++i)
        dist[i] = Inf;
    ok = 1;
}

void BellmanFord(int start) {
    Queue.push(start);
    dist[start] = 0;
    contor[start] = 1;
    while (!Queue.empty()) {
        int nod = Queue.front();
        Queue.pop();
        in_q[nod] = 0;
        for (int i = 0; i < G[nod].size(); ++i) {
            int vecin = G[nod][i].first;
            int cost = G[nod][i].second;
            if (dist[vecin] > dist[nod] + cost) {
                dist[vecin] = dist[nod] + cost;
                if (!in_q[vecin]) {
                    in_q[vecin] = 1;
                    ++contor[vecin];
                    Queue.push(vecin);
                }
            }
            if (contor[vecin] >= n) {
                ok = 0;
                return;
            }
        }
    }
}

void Solve() {
    Initializare();
    BellmanFord(1);
}

void Afisare() {
    ofstream out("bellmanford.out");
    if (!ok)
        out << "Ciclu negativ!";
    else
        for (int i = 2; i <= n; ++i)
            out << dist[i] << ' ';
    out << '\n';
    out.close();
}

int main () {
    Citire();
    Solve();
    Afisare();
    return 0;
}