Cod sursa(job #2637063)

Utilizator BAlexandruBorgovan Alexandru BAlexandru Data 21 iulie 2020 01:25:57
Problema Algoritmul lui Dijkstra Scor 0
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.28 kb
#include <fstream>
#include <vector>
#include <queue>

using namespace std;

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

class compare
{
public:
    bool operator() (pair < int, int > a, pair < int, int > b)
    {
        return a.second > b.second;
    }
};

int n, m;
int d[50001];
bool u[50001];
vector < pair < int, int > > v[50001];
priority_queue < pair < int, int >, vector < pair < int, int > >, compare > pq;

void dijkstra()
{
    for (int i=2; i<=n; i++)
        d[i] = INT_MAX;

    pq.push({1, 0});
    while (!pq.empty())
    {
        int nod = pq.top().first;
        int dist = pq.top().second;
        pq.pop();

        if (u[nod])
            continue;

        u[nod] = 1;
        d[nod] = min(d[nod], dist);

        for (auto it : v[nod])
            if (!u[it.first])
                pq.push({it.first, dist + it.second});
    }
}

int main()
{
    f >> n >> m;
    for (int i=1; i<=m; i++)
    {
        int nod1, nod2, lg;
        f >> nod1 >> nod2 >> lg;
        v[nod1].push_back({nod2, lg});
        v[nod2].push_back({nod1, lg});
    }

    dijkstra();

    for (int i=2; i<=n; i++)
        if (d[i] == INT_MAX)
            g << 0 << " ";
        else
            g << d[i] << " ";

    return 0;
}