Cod sursa(job #3246427)

Utilizator andreiomd1Onut Andrei andreiomd1 Data 2 octombrie 2024 23:21:48
Problema Algoritmul lui Dijkstra Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.64 kb
#include <fstream>
#include <vector>
#include <queue>

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

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

static constexpr int nMAX = ((int)(5e4) + 4);
static constexpr int INF = ((int)(1e9));

int n;
vector<edge> G[nMAX];

auto cmp = [](const edge &x, const edge &y)
{
    if (!(x.first < y.first))
        return 1;
    return 0;
};

void add_edge(const int x, const int y, const int cost)
{
    G[x].push_back({cost, y});

    return;
}

void load_graph()
{
    int m = 0;

    f >> n >> m;

    int x = 0, y = 0, v = 0;

    for (int i = 1; i <= m; ++i)
    {
        f >> x >> y >> v,
            add_edge(x, y, v);
    }

    return;
}

int main()
{
    load_graph();

    vector<int> d((n + 1), INF);
    vector<bool> completed((n + 1), false);

    priority_queue<edge, vector<edge>, decltype(cmp)> H(cmp);

    d[1] = 0, completed[1] = true;
    for (const edge &e : G[1])
        if (e.first < d[e.second])
            d[e.second] = e.first, H.push(e);

    while (!H.empty())
    {
        while (!H.empty() && completed[H.top().second])
            H.pop();

        if (H.empty())
            break;

        int node = H.top().second;
        H.pop();

        completed[node] = true;

        for (const edge &e : G[node])
            if (!completed[e.second])
                if (d[node] + e.first < d[e.second])
                    d[e.second] = d[node] + e.first,
                    H.push({d[e.second], e.second});
    }

    for (int i = 2; i <= n; ++i)
    {
        g << ((d[i] == INF) ? 0 : d[i]);

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

    return 0;
}