Cod sursa(job #2505793)

Utilizator matei123Biciusca Matei matei123 Data 7 decembrie 2019 11:04:30
Problema Algoritmul Bellman-Ford Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.23 kb
#include <fstream>
#include <queue>
#include <vector>
using namespace std;
ifstream f("bellmanford.in"); ofstream g("bellmanford.out");
const int INF=1e9;
queue <int> q;
vector <pair<int,int>> G[50005];
int n,m,x,y,c,i,d[50005],nr[50005];
bool viz[50005];
bool Bellmanford()
{   bool ciclu=false;
    while(!q.empty() && !ciclu)
    {   x=q.front();
        q.pop();
        viz[x]=false;
        for(int i=0;i<G[x].size();i++)
        {   if(nr[G[x][i].second]>n) ciclu=true;
            if(d[x]+G[x][i].first<d[G[x][i].second])
            {   d[G[x][i].second]=d[x]+G[x][i].first;
                if(!viz[G[x][i].second])
                {   q.push(G[x][i].second);
                    viz[G[x][i].second]=true;
                }
                nr[G[x][i].second]=nr[x]+1;
                if(nr[G[x][i].second]>n) ciclu=true;
            }
        }
    }
    return ciclu;
}
int main()
{   f>>n>>m;
    for(i=1; i<=m; ++i)
    {   f>>x>>y>>c;
        G[x].push_back({c,y});
    }
    for(int i=1; i<=n; i++) d[i]=INF;
    viz[1]=true; nr[1]=1;
    q.push(1); d[1]=0;
    if(Bellmanford())
        g<<"Ciclu negativ!"<<'\n';
    else
        for(i=2; i<=n; i++)
            g<<d[i]<<' ';
    return 0;
}