Cod sursa(job #809763)

Utilizator romircea2010FMI Trifan Mircea Mihai romircea2010 Data 8 noiembrie 2012 23:19:28
Problema Algoritmul Bellman-Ford Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.5 kb
#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
#define INF 2000000000

using namespace std;

int n, m, d[50005], ordin[50005];
struct NOD
{
    int x, cost;
};
vector <NOD> a[50005];
queue <int> q;

inline void Read()
{
    ifstream f("bellmanford.in");
    f>>n>>m;
    int x, y, cost;
    NOD aux;
    for(int i = 1; i<=m; i++)
    {
        f>>x>>aux.x>>aux.cost;
        a[x].push_back(aux);
    }
    f.close();
}

inline bool BellmanFord()
{
    int i, x, cost;
    vector <NOD>::iterator it, final;
    NOD aux;
    for(i=1; i<=n; i++)
        d[i] = INF;
    d[1] = 0;
    q.push(1);
    while(!q.empty())
    {
        x = q.front();
        q.pop();
        it = a[x].begin();
        final = a[x].end();
        for(; it!=final; it++)
        {
            aux = *it;
            if (d[aux.x] > d[x] + aux.cost)
            {
                d[aux.x] = d[x] + aux.cost;
                q.push(aux.x);
                ordin[aux.x] = ordin[x] + 1;

            if (ordin[aux.x] > n)
                return true;
            }
        }
    }
    return false;
}

inline void Write(bool ciclu)
{
    ofstream g("bellmanford.out");
    if(ciclu)
    {
        g<<"Ciclu negativ!\n";
    }
    else
    {
        int i;
        for(i=2; i<=n; i++)
            g<<d[i]<<" ";
        g<<"\n";
    }
    g.close();
}


int main()
{
    Read();
    bool ciclu;
    ciclu = BellmanFord();
    Write(ciclu);
    return 0;
}