Cod sursa(job #1305468)

Utilizator SagunistuStrimbu Alexandru Sagunistu Data 29 decembrie 2014 19:53:45
Problema Algoritmul Bellman-Ford Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.68 kb
#include <iostream>
#include <queue>
#include <fstream>
#include <cstring>
#include <vector>
#define inf 0x3f3f3f3f
#define cost first
#define vecin second
#define nmax 50005

using namespace std;

ifstream fin("bellmanford.in");
ofstream fout("bellmanford.out");

int n,m;
queue<int> q;
vector <pair<int,int> >g[nmax];
int viz[nmax],nrit[nmax],d[nmax];
bool ciclu;

void citire()
{
    int x,y,c;
    fin>>n>>m;
    for(int i=1;i<=m;i++)
    {
        fin>>x>>y>>c;
        g[x].push_back(make_pair(c,y));
    }
    memset(d,inf,sizeof(d));
    memset(viz,0,sizeof(viz));
    memset(nrit,0,sizeof(nrit));
}

void bellmanford()
{
    int k;
    ciclu=0;
    d[1]=0;
    q.push(1);
    while(!q.empty()&&!ciclu)
    {
        k=q.front();
        viz[k]=0;
        q.pop();
        vector<pair<int,int> >::iterator ii;
        for(ii=g[k].begin();ii!=g[k].end();++ii)
            if(d[ii->vecin]>d[k]+ii->cost)
            {
                d[ii->vecin]=d[k]+ii->cost;
                if(viz[ii->vecin]==0)
                {
                    if(nrit[ii->vecin]>n)
                    {
                        ciclu=1;
                        break;
                    }
                    else
                    {
                        viz[ii->vecin]=1;
                        q.push(ii->vecin);
                        nrit[ii->vecin]++;
                    }
                }
            }
    }
}

void afisare()
{
    if(ciclu)
    {
        fout<<"Ciclu negativ!";
        return;
    }
    for(int i=2;i<=n;i++)
        fout<<d[i]<<" ";
}

int main()
{
    citire();
    bellmanford();
    afisare();
    return 0;
}