Cod sursa(job #2869798)

Utilizator servus2022Stefan Tonut servus2022 Data 11 martie 2022 20:36:17
Problema Algoritmul lui Dijkstra Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.86 kb
#include <fstream>
#include <vector>
#include <queue>

using namespace std;

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

typedef pair < int, int > PII;

const int NMAX = 5e4 + 1;
const int Source = 1;
const int INF = 1e9;

int N;
vector < PII > G[NMAX];

int d[NMAX];
bool Sel[NMAX];

auto cmp = [] (PII A, PII B)
{
    if(!(A.first < B.first))
        return 1;

    return 0;
};
priority_queue < PII, vector < PII >, decltype(cmp) > H(cmp);

static inline void Read ()
{
    f.tie(nullptr);

    int M = 0;
    f >> N >> M;

    for(int i = 1; i <= M; ++i)
    {
        int x = 0, y = 0, c = 0;
        f >> x >> y >> c;

        G[x].push_back({c, y});
    }

    return;
}

static inline void Initialize (int X)
{
    for(int i = 1; i <= N; ++i)
        if(i == X)
            d[i] = 0, Sel[i] = true;
        else
            d[i] = INF, Sel[i] = false;

    return;
}

static inline void Expand (int Node)
{
    for(auto it : G[Node])
        if(it.first < d[it.second])
            d[it.second] = it.first, H.push(it);

    return;
}

static inline void Dijkstra (int Start)
{
    Initialize(Start);

    Expand(Start);

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

        if(H.empty())
            break;

        PII Top = H.top();
        H.pop();

        int Dist = Top.first, Node = Top.second;

        Sel[Node] = 1;

        for(auto it : G[Node])
            if(Dist + it.first < d[it.second])
                d[it.second] = Dist + it.first, H.push({d[it.second], it.second});
    }

    return;
}

int main()
{
    Read();

    Dijkstra(Source);

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

        if(i != N)
            g << ' ';
    }

    g << '\n';

    return 0;
}