Cod sursa(job #2114591)

Utilizator CriogeniXBociat Daniel Tiberiu CriogeniX Data 25 ianuarie 2018 17:42:32
Problema Algoritmul Bellman-Ford Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.42 kb
#include <fstream>
#include <vector>
#include <queue>
using namespace std;

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

const int NMax = 50005;
const int oo = 1000000000;
int N,M,D[NMax];
bool InQ[NMax];
int NrQ[NMax];
vector < pair <int, int> > G[NMax];
queue <int> Q,QQ;

void Read()
{
  fin>>N>>M;
  for(int i = 1; i <= M ; ++i)
    {
      int x,y,c;
      fin>>x>>y>>c;
      G[x].push_back(make_pair(y,c));
    }
}

int BellmanFord()
{
  int Ok = 1;

  for(int i = 2; i <= N; ++i)
    D[i] = oo;

  Q.push(1);
  InQ[1] = 1;
  NrQ[1] = 1;

     while(!Q.empty() && Ok != -1)
     {
       int i = Q.front(); Q.pop(); InQ[i] = 0;

        for(int j = 0; j < (int) G[i].size(); ++j)
          {
            int Vecin = G[i][j].first, Cost = G[i][j].second;
            if(D[Vecin] > D[i] + Cost)
              {
                D[Vecin] = D[i] + Cost;
                if(InQ[Vecin] == 0)
                {
                  Q.push(Vecin);
                  InQ[Vecin] = 1;
                  NrQ[Vecin]++;
                  if(NrQ[Vecin] > N)
                    Ok = -1;
                }
              }
          }
      }

   return Ok;
}

void Print()
{
  for(int i = 2; i <= N ; ++i)
    fout<<D[i]<<" ";
  fout<<"\n";
}

int main()
{
    Read();
    if(BellmanFord()==-1)
      fout<<"Ciclu negativ!\n";
    else
      Print();
    return 0;
}