Cod sursa(job #2484282)

Utilizator iulianarsenoiuArsenoiu Iulian iulianarsenoiu Data 30 octombrie 2019 21:15:02
Problema Algoritmul Bellman-Ford Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.3 kb
#include <fstream>
#include <queue>
#include <vector>

using namespace std;
ifstream f("bellmanford.in");
ofstream g("bellmanford.out");
const int INF=0x3f3f3f3f;
queue <int> q;
vector <pair<int,int>> G[50005];
int n,m,x,y,c,i,d[50005],nr[50005];
bool sel[50005];
bool Bellmanford()
{
    for(int i=1; i<=n; i++)
        d[i]=INF,sel[i]=false;
    sel[1]=true;
    nr[1]=1;
    q.push(1);
    d[1]=0;
    bool done=false;
    while(!q.empty() && !done)
    {
        x=q.front();
        q.pop();
        sel[x]=false;
        for(auto it : G[x])
        {
            if(nr[it.second]>n)
                done=true;
            if(d[x]+it.first<d[it.second])
            {
                d[it.second]=d[x]+it.first;
                if(!sel[it.second])
                {
                    q.push(it.second);
                    sel[it.second]=true;
                }
                nr[it.second]=nr[x]+1;
                if(nr[it.second]>n)
                    done=true;
            }
        }
    }
    return done;
}
int main()
{
    f>>n>>m;
    for(i=1; i<=m; ++i)
    {
        f>>x>>y>>c;
        G[x].push_back({c,y});
    }
    if(Bellmanford())
        g<<"Ciclu negativ!"<<'\n';
    else
        for(i=2; i<=n; i++)
            g<<d[i]<<' ';
    return 0;
}