Cod sursa(job #2167448)

Utilizator RazorBestPricop Razvan Marius RazorBest Data 13 martie 2018 21:47:43
Problema Algoritmul Bellman-Ford Scor 35
Compilator cpp Status done
Runda Arhiva educationala Marime 1.62 kb
#include <fstream>
#define oo 0x7fffffff
using namespace std;

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

struct graf
{
    int nod, c;
    graf *next;
};

struct muchie
{
    int x, y, c;
} M[250001];

int n, m, dist[50001], a[50001], len;
graf * adj[50001];

void add(int x, int y,  int c)
{
    graf *g = new graf;
    g->nod = y;
    g->c = c;
    g->next = adj[x];
    adj[x] = g;
}

bool bellman()
{
    for (int i = 1; i <= n; i++)
        dist[i] = oo;
    dist[1] = 0;

    a[0] = 1;
    len = 1;
    for (int i = 1; i < n; i++)
    {
        int new_len = len;
        for (int j = 0; j < len; j++)
        {
            int nod = a[j], d = dist[nod];
            graf *q = adj[nod];
            while (q)
            {
                if (dist[q->nod] == oo)
                {
                    a[new_len++] = q->nod;
                }
                dist[q->nod] = min(dist[q->nod], d + q->c);
                q = q->next;
            }
            len = new_len;
        }
    }
    for (int j = 0; j < len; j++)
    {
        int nod = a[j], d = dist[nod];
        graf *q = adj[nod];
        while (q)
        {
            if (d + q->c < dist[q->nod])
                return false;
            q = q->next;
        }
    }


    return true;
}

int main()
{
    int x, y, c;

    fin >> n >> m;
    for (int i = 0; i < m; i++)
    {
        fin >> x >> y >> c;
        add(x, y, c);
    }

    if(!bellman())
        fout << "Ciclu negativ!";
    else
        for (int i = 2; i <= n; i++)
            fout << dist[i] << ' ';

}