Cod sursa(job #2417944)

Utilizator ALEx6430Alecs Andru ALEx6430 Data 2 mai 2019 13:57:33
Problema Algoritmul Bellman-Ford Scor 55
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.48 kb
#include <fstream>
#include <vector>
#include <queue>
#include <set>
#define INF 100000000
using namespace std;

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

vector<int> d;

struct mycomp
{
    bool operator() (int &a, int &b)
    {
        return d[a] > d[b];
    }
};

int main()
{
    int n, m;
    in >> n >> m;

    d.assign(n+1,INF);
    d[1] = 0;

    vector<pair<int,int>> v[n+1];

    for(int i = 0; i < m; i++)
    {
        int x, y, c;
        in >> x >> y >> c;

        v[x].push_back({y,c});
    }

    vector<bool> inQ(n+1,false);
    priority_queue<int,vector<int>,mycomp> pq;

    pq.push(1);

    set<int> s;

    while(!pq.empty())
    {
        int nod = pq.top();
        pq.pop();

        inQ[nod] = false;

        for(size_t i = 0; i < v[nod].size(); i++)
        {
            int act = v[nod][i].first;
            int cost = v[nod][i].second;

            if(d[nod]+cost < d[act])
            {
                d[act] = d[nod]+cost;

                if(s.find(act) != s.end() && d[act] < 0)
                {
                    out << "Ciclu negativ!";
                    return 0;
                }

                if(!inQ[act])
                {
                    inQ[act] = true;
                    pq.push(act);
                }
            }
        }

        s.insert(nod);
    }

    for(int i = 2; i <= n; i++) out << (d[i] == INF ? 0 : d[i]) << ' ';

    return 0;
}