Cod sursa(job #2734879)

Utilizator BogdanFarcasBogdan Farcas BogdanFarcas Data 1 aprilie 2021 16:16:10
Problema Algoritmul Bellman-Ford Scor 0
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.35 kb
#include <fstream>
#include <vector>
#include <queue>

using namespace std;

ifstream cin("bellmanford.in");
ofstream cout("bellmanford.out");

const int N=50005;
const int INF=1e9;

int n,m,k,x,y,cost;
int d[N];
bool nrq[N],inq[N],ok;
vector< pair<int,int> >v[N];
queue<int>q;

void bellman_ford(int start)
{
    q.push(start);
    for(int i=1;i<=n;i++)
    {
        d[i]=INF;
    }
    d[start]=0;
    inq[start]=true;
    while(!q.empty())
    {
        int nod=q.front();
        nrq[nod]++;
        inq[nod]=false;
        if(nrq[nod]==n)
        {
            ok=false;
            break;
        }
        q.pop();
        for(auto x:v[nod])
        {
            int vecin=x.first;
            int cost=x.second;
            if(d[vecin]>d[nod]+cost)
            {
                d[vecin]=d[nod]+cost;
                if(inq[vecin]==false)
                {
                    q.push(vecin);
                    inq[nod]=true;
                }
            }
        }
    }
}

int main()
{
    cin>>n>>m;
    for(int i=1;i<=m;i++)
    {
        cin>>x>>y>>cost;
        v[x].push_back(make_pair(y,cost));
    }
    ok=true;
    bellman_ford(1);
    if(ok==false)
    {
        cout<<"Ciclu negativ!";
    }
    else
    for(int i=2;i<=n;i++)
    {
        cout<<d[i]<<" ";
    }
    return 0;
}