Cod sursa(job #2041918)

Utilizator PaulTPaul Tirlisan PaulT Data 17 octombrie 2017 21:15:40
Problema Algoritmul lui Dijkstra Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.31 kb
#include <fstream>
#include <vector>
#include <queue>
using namespace std;

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

using VI = vector<int>;
using PI = pair<int, int>;
using VP = vector<PI>;

const int Inf = 0x3f3f3f3f;
int n, m;
vector<VP> G;
VI d;

void ReadGraph();
void Dijkstra(int x, VI& d);

int main()
{
    ReadGraph();
    Dijkstra(1, d);
    for (int i = 2; i <= n; i++)
        if (d[i] == Inf)
            fout << "0 ";
        else
            fout << d[i] << ' ';

    fin.close();
    fout.close();
}

void Dijkstra(int x, VI& d)
{
    priority_queue<PI, VP, greater<PI>> Q;
    d = VI(n + 1, Inf);
    d[x] = 0;
    Q.push({0, x});
    int y, dx, w;
    while (!Q.empty())
    {
        x = Q.top().second;
        dx = Q.top().first;
        Q.pop();
        if (dx > d[x])
            continue;
        for (const auto& p : G[x])
        {
            y = p.first;
            w = p.second;
            if (d[y] > d[x] + w)
            {
                d[y] = d[x] + w;
                Q.push({d[y], y});
            }
        }
    }
}

void ReadGraph()
{
    fin >> n >> m;
    G = vector<VP>(n + 1);
    int x, y, w;
    for (int i = 1; i <= m; i++)
    {
        fin >> x >> y >> w;
        G[x].push_back({y, w});
    }
}