Cod sursa(job #3242374)

Utilizator andreiomd1Onut Andrei andreiomd1 Data 11 septembrie 2024 18:48:09
Problema Algoritmul Bellman-Ford Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.58 kb
#include <fstream>
#include <queue>

using namespace std;
using PII = pair<int, int>;

ifstream f("bellmanford.in");
ofstream g("bellmanford.out");

static constexpr int nMAX = ((int)(5e4) + 1),
                     INF = ((int)(1e9));

int n;

vector<PII> G[nMAX];

static void add_edge(const int u, const int v, const int w)
{
    G[u].push_back({w, v});
    return;
}

static void read()
{
    f.tie(nullptr);

    int m = 0;
    f >> n >> m;

    for (int i = 1; i <= m; ++i)
    {
        int u = 0, v = 0, w = 0;
        f >> u >> v >> w;

        add_edge(u, v, w);
    }

    return;
}

int main()
{
    read();

    queue<int> Q = {};
    vector<bool> in_queue((n + 1), false);
    vector<int> d((n + 1), INF);
    vector<int> counts((n + 1), 0);

    Q.push(1), in_queue[1] = true, d[1] = 0, counts[1] = 1;

    while (!Q.empty())
    {
        int node = Q.front();
        Q.pop();

        in_queue[node] = false;

        for (const PII &it : G[node])
            if (d[node] + it.first < d[it.second])
            {
                d[it.second] = d[node] + it.first;

                if (in_queue[it.second])
                    continue;

                ++counts[it.second];
                if (counts[it.second] >= n)
                {
                    g << "Ciclu negativ!\n";
                    exit(0);
                }

                Q.push(it.second), in_queue[it.second] = true;
            }
    }

    for (int i = 2; i <= n; ++i)
    {
        g << ((d[i] == INF) ? (-1) : d[i]);

        if (i == n)
            g << '\n';
        else
            g << ' ';
    }

    return 0;
}