Cod sursa(job #1852231)

Utilizator Cudrici_CarinaCudrici Carina Cudrici_Carina Data 20 ianuarie 2017 17:01:52
Problema Algoritmul lui Dijkstra Scor 60
Compilator cpp Status done
Runda Arhiva educationala Marime 1.34 kb
#include <fstream>
#include <vector>
#include <queue>
using namespace std;

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

#define PII pair<int, int>
#define VI vector<int>
#define pb push_back

const int Inf = 0x3f3f3f3f;
void ReadGraph();
void Dijkstra(int S, VI& d);

vector<vector<PII> > G;
VI d;
int n, m;

int main()
{
    ReadGraph();
    Dijkstra(1, d);

    for (int i = 2; i <= n; ++i)
        if ( d[i] != Inf )
            fout << d[i] << ' ';
        else
            fout << 0 << ' ';

    fout.close();

}

void ReadGraph()
{

    int x, y, w;
    fin >> n >> m;
    G.resize(n + 1);
    while ( m-- )
    {
        fin >> x >> y >> w;
        G[x].pb({w, y});
      //  G[y].pb({w, x});
    }
    fin.close();
}
void Dijkstra(int x, VI& d) // O(m * log n)
{
    d = VI(n + 1, Inf);
    d[x] = 0;
    priority_queue<PII, vector<PII>, greater<PII> > Q;

    for ( Q.push({0, x}); !Q.empty(); Q.pop() )
    {
        x = Q.top().second;
        int dx = Q.top().first;
        if ( dx > d[x] )
            continue;
 for (size_t i=0;i<G[x].size();i++)
        {   PII p=G[x][i];
            int y = p.second, w = p.first;
            if ( d[y] > d[x] + w)
            {
                d[y] = d[x] + w;
                Q.push({d[y], y});
            }
        }
    }
}