Cod sursa(job #2365264)

Utilizator Mihai_CiortescuCiortescu Mihai Mihai_Ciortescu Data 4 martie 2019 12:43:17
Problema Algoritmul Bellman-Ford Scor 90
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.44 kb
#include <fstream>
#include <queue>
#include <vector>
#define NMAX 50015
#define INF 10000000000

using namespace std;

ifstream fin("bellmanford.in");
ofstream fout("bellmanford.out");
int n, start=1, i, k, vf;
int cmin[NMAX]; //cmin[x] costul drumului de cost minim de la start la x
int nr[NMAX]; //nr[x] de cate ori s-a acyualizat costul drumului de cost minim de la start la x

struct varf{int x; int c;};

vector <varf> G[NMAX];
queue <int> C;

void citire();
bool bellman();


int main ()
{
    citire();
    bellman();
    if (!bellman())
        fout<<"Ciclu negativ!";
    else
        for (i=2; i<=n; i++)
        if (cmin[i]==INF)
        fout<<"-1"<<' ';
        else fout<<cmin[i]<<' ';
    fout.close();
  return 0;
}

void citire()
{
    int i, j, c, m;
    varf aux;
    fin>>n>>m;
    for (k=0; k<m; k++)
    {
        fin>>i>>j>>c;
        aux.x=j; aux.c=c;
        G[i].push_back(aux);
    }
}

bool bellman() //0 fara solutie si 1 pt soluti
{int i, vf;
  for (i=1; i<=n; i++)
    cmin[i]=INF;
  cmin[start]=0;
  C.push(start);
  while (!C.empty())
  {
    vf=C.front();
    C.pop();
    //parcurg lista de adiacenta a lui x
    for (i=0; i<G[vf].size(); i++)
        if (cmin[G[vf][i].x]>cmin[vf]+G[vf][i].c)
    {
        cmin[G[vf][i].x]=cmin[vf]+G[vf][i].c;
        nr[G[vf][i].x]++;
        if (nr[G[vf][i].x]==n) return 0;
        C.push(G[vf][i].x);
    }
  }
  return 1;
}