Cod sursa(job #2359212)

Utilizator grecubogdanGrecu Bogdan grecubogdan Data 28 februarie 2019 18:44:13
Problema Algoritmul Bellman-Ford Scor 0
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.38 kb
#include <fstream>
#include <vector>
#include <queue>
using namespace std;
ifstream f("bellmanford.in");
ofstream g("bellmanford.out");
const int oo=(1<<30);
int *nr[50005];
int n,m,i,D[50005],viz[50005],x,y,z;
vector<pair<int,int> >G[250005];
struct compara
{
    bool operator()(int x, int y)
    {
        return D[x]>D[y];
    }
};
priority_queue<int, vector<int>, compara> q;
int bf(int ns)
{
    for(i=1;i<=n;i++)
        D[i]=oo;
    D[ns]=0;
    q.push(ns);
    viz[ns]=1;
    while(!q.empty())
    {
        int nc=q.top();
        q.pop();
        viz[nc]=0;
        for(i=0;i<G[nc].size();i++)
        {
            int vecin,cost;
            vecin=G[nc][i].first;
            cost=G[nc][i].second;
            if(D[nc]+cost<D[vecin])
            {
                ++nr[nc][i];
                if(nr[nc][i]==n)
                    return 1;
                D[vecin]=D[nc]+cost;
                if(viz[vecin]==0)
                {
                    q.push(vecin);
                    viz[vecin]=1;
                }
            }
        }
    }
    return 0;
}
int main()
{
 f>>n>>m;
 for(i=1;i<=m;i++)
 {
     f>>x>>y>>z;
     G[x].push_back(make_pair(y,z));
 }
 if(bf(1))
 {
     g<<"exist ciclu negativ";
     return 0;
 }
 for(i=2;i<=n;i++)
 {
     if(D[i]!=oo)
        g<<D[i]<<" ";
     else g<<"0 ";
 }
 return 0;
}