Cod sursa(job #2803005)

Utilizator ptr22222Petru Popescu ptr22222 Data 19 noiembrie 2021 11:28:03
Problema Algoritmul Bellman-Ford Scor 45
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 3.1 kb
#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
#include <stack>
#include <algorithm>

using namespace std;

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

const int nmax = 50001;
const int inf = (1<<30);

class Graf
{
private:
    bool orientat;
    int nrNoduri;
    vector <int> listaAdiacenta[nmax];
    vector <pair <int, int>> listaAdiacentaCost[nmax];
public:
    Graf(int nrNoduri = 0, bool orientat = false);
    void adaugaMuchieCost(int, int, int);
    void citireMuchii(int);
    void citireMuchiiCost(int);
    vector<int> BFS(int);
    void DFS(int, bool*);
    int nrComponenteConexe();
    void DFSStiva(int nodcurent, bool *, stack<int> &);
    void sortareTopologica();
    void TarjanCTC(int&, int, int*, int*, bool*, stack <int> &, vector<vector<int>> &);
    void CTC();
    void TarjanBC(int&, int, int, int*, int*, stack <int>&, vector<vector<int>>&);
    void BC();
    void TarjanMC(int&, int, int, int*, int*, vector<pair<int,int>>&);
    void MC();
    vector <int> citireHakimi();
    bool Hakimi(vector <int>);
    vector <int> Dijkstra(int);
    pair<int, vector <pair <int, int>>> Prim(int);
    vector <int> BellmanFord(int);
};

Graf :: Graf(int nrNoduri, bool orientat) : nrNoduri(nrNoduri), orientat(orientat)
{
    this->nrNoduri = nrNoduri;
    this->orientat = orientat;
}

void Graf::adaugaMuchieCost(int nod1, int nod2, int cost)
{
    listaAdiacentaCost[nod1].push_back(make_pair(nod2, cost));
}

void Graf::citireMuchiiCost(int nrMuchii)
{
    int nod1, nod2, cost;
    for(int i = 0; i < nrMuchii; i++)
    {
        in >> nod1 >> nod2 >> cost;
        adaugaMuchieCost(nod1, nod2, cost);
        if(!orientat)
        {
            adaugaMuchieCost(nod2, nod1, cost);
        }
    }
}

vector <int> Graf::BellmanFord(int nodStart)
{
    vector <int> cost(nmax, inf);
    queue<int> coada;
    bool esteInCoada[nmax] = {false};
    vector <int> nrIteratii(nmax,0);
    cost[nodStart] = 0;
    coada.push(nodStart);
    esteInCoada[nodStart] = true;
    nrIteratii[nodStart]++;
    while(!coada.empty())
    {
        int nodCurent = coada.front();
        coada.pop();
        esteInCoada[nodCurent] = false;
        if(nrIteratii[nodCurent] == nrNoduri)
        {
            out << "Ciclu negativ!";
            cost.clear();
            return cost;
        }
        nrIteratii[nodCurent]++;
        for (auto vecin:listaAdiacentaCost[nodCurent])
        {
            if(cost[nodCurent] + vecin.second < cost[vecin.first])
            {
                cost[vecin.first] = cost[nodCurent] + vecin.second;
                if(!esteInCoada[vecin.first])
                {
                    coada.push(vecin.first);
                    esteInCoada[vecin.first] = true;
                    nrIteratii[vecin.first]++;
                }
            }
        }
    }

    return cost;
}

int main()
{
    int n, m;
    in >> n >> m;
    Graf g(n,true);
    g.citireMuchiiCost(m);
    vector <int> rezultat;
    rezultat = g.BellmanFord(1);
    if(!rezultat.empty())
    {
        for(int i = 2; i <= n; i++)
        {
            out << rezultat[i] << " ";
        }
    }
    return 0;
}