Cod sursa(job #2219589)

Utilizator dfettiDaniel Fetti dfetti Data 9 iulie 2018 13:33:21
Problema Algoritmul lui Dijkstra Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.54 kb
// OK
#include <fstream>
#include <bitset>
#include <queue>
#include <vector>
using namespace std;
  
using VI = vector<int>;
using PII = pair<int, int>;
using VPII = vector<PII>;
const int Inf = 0x3f3f3f3f;
 
struct Pair {
    int y, dist;
    bool operator < (const Pair& p) const
    {
        return dist > p.dist;
    }
};
 
priority_queue<Pair> Q;
vector<VPII> G; 
vector<int> d;
int n, m;
 
void ReadGraph();
void Dijkstra(int k);
void Write();
 
int main()
{
    ReadGraph();
     
    Dijkstra(1);
    Write();
}
 
void Dijkstra(int k)
{
    int y, w, dist;      // costul muchiei
    d = vector<int>(n + 1, Inf);
     
    d[k] = 0;
    Q.push({k, 0});
     
    while ( !Q.empty() )
    {
        k = Q.top().y; dist = Q.top().dist;
        Q.pop();
        if ( dist > d[k] )
            continue;
        for (const auto& e : G[k])
        {
            y = e.first; w = e.second; 
            if ( d[y] > d[k] + w )
            {
                d[y] = d[k] + w;
                Q.push({y, d[y]});
            }
        }
    }
}
 
void ReadGraph()
{
    ifstream fin("dijkstra.in");
    fin >> n >> m;
    G.resize(n + 1);
    int x, y, w; 
    for (int e = 0; e < m; ++e)
    {
        fin >> x >> y >> w;
        G[x].push_back({y, w}); 
    }
    fin.close();
}
 
void Write()
{
    ofstream fout("dijkstra.out"); 
    for (int i = 2; i <= n; ++i)
        if ( d[i] != Inf )
            fout << d[i] << ' ';
        else
            fout << 0 << ' ';
    fout.close();
}