Cod sursa(job #2860792)

Utilizator AdrianDiaconitaAdrian Diaconita AdrianDiaconita Data 3 martie 2022 09:21:42
Problema Algoritmul Bellman-Ford Scor 0
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.84 kb
#include <iostream>
#include <fstream>
#include <queue>
#include <vector>
 
using namespace std;
 
ifstream fin("bellmanford.in");
ofstream fout("bellmanford.out");

const int NMAX = 50001;
const int inf = 1 << 30;
int N, D[NMax], vizitat[NMax], ok;
bool inCoada[NMax];
 
vector < pair<int, int> > G[NMax];
 
struct Compara
{
    bool operator() (int x, int y)
    {
        return D[x] > D[y];
    }
};
priority_queue < int, vector<int>, Compara > Coada;
 
void Citire()
{
    int A, B, C, M;
 
    fin >> N >> M;
 
    for(int i=1; i<=M; ++i)
    {
        fin >> A >> B >> C;
        G[A].push_back( make_pair(B, C) );
    }
}
 
void BellmanFord(int nodStart)
{
    for(int i=1; i<=N; ++i)
    {
        D[i] = inf;
        vizitat[i] = 0;
    }
 
    ok = 0;
    D[nodStart] = 0;
    Coada.push(nodStart);
    inCoada[nodStart] = true;
 
    while( !Coada.empty() )
    {
        int nodCurent = Coada.top();
        Coada.pop();
        inCoada[nodCurent] = false;
 
        vizitat[nodCurent] ++;
        if(vizitat[nodCurent] >= N)
        {
            ok = 1;
            break;
        }
 
        for(unsigned int i = 0; i < G[nodCurent].size(); ++i)
        {
            int Vecin = G[nodCurent][i].first;
            int Cost = G[nodCurent][i].second;
 
            if(D[nodCurent] + Cost < D[Vecin])
            {
                D[Vecin] = D[nodCurent] + Cost;
 
                if(inCoada[Vecin] == false)
                {
                    Coada.push(Vecin);
                    inCoada[Vecin] = true;
                }
            }
        }
    }
}
 
int main()
{
    Citire();
    BellmanFord(1);
 
    if(ok) fout << "Ciclu negativ!";
 
    else
        for(int i = 2; i <= N; ++i)
            if(D[i] != inf)
                fout << D[i] << ' ';
 
    return 0;
}