Cod sursa(job #1362418)

Utilizator gabriel.bjgGabriel b. gabriel.bjg Data 26 februarie 2015 12:31:00
Problema Algoritmul Bellman-Ford Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.64 kb
#include <fstream>
#include <vector>
#include <queue>
#include <cstring>
#define INF 0x3f3f3f3f
#define NMAX 50005
using namespace std;
ifstream fin("bellmanford.in");
ofstream fout("bellmanford.out");
int n,m;
vector <pair<int,int> > G[NMAX];
vector <int> cnt_in_queue(NMAX, 0);
int dmin[NMAX];
int negative_cycle = false;
void citire()
{
    int a,b,c;
    fin>>n>>m;
    for(int i=1;i<=m;i++)
    {
        fin>>a>>b>>c;
        G[a].push_back(make_pair(b,c));
    }
}
void prog()
{
    bool in[NMAX];
    int nod;
    queue <int> Q;
    memset(dmin, INF, sizeof(dmin));
    memset(in, false, sizeof(in));
    dmin[1]=0;
    in[1]=true;
    Q.push(1);
    while(!Q.empty() && !negative_cycle)
    {
        nod=Q.front();
        in[nod]=false;
        Q.pop();
        for(vector<pair<int,int> >::iterator it=G[nod].begin(); it!=G[nod].end(); ++it)
            if(dmin[nod]+it->second < dmin[it->first])
            {
                dmin[it->first]=dmin[nod]+it->second;
                if(!in[it->first])
                {
                    if (cnt_in_queue[it->first] > n)
                        negative_cycle = true;
                    else
                    {
                        Q.push(it->first);
                        in[it->first]=true;
                        cnt_in_queue[it->first]++;
                    }
                }
            }
    }

}
int main()
{
    citire();
    prog();
    if(!negative_cycle)
    {
        for (int i = 2; i <= n; ++i)
        fout << (dmin[i] < INF ? dmin[i] : 0) << " ";
    }
    else
        fout<<"Ciclu negativ!\n";
    fout.close();
}