Cod sursa(job #1842589)

Utilizator crysstyanIacob Paul Cristian crysstyan Data 7 ianuarie 2017 11:50:20
Problema Algoritmul lui Dijkstra Scor 20
Compilator cpp Status done
Runda Arhiva educationala Marime 1.4 kb
#include <fstream>
#include <vector>
#include <queue>
#include <algorithm>
#define NMAX 50005
#define inf 2000000000

using namespace std;

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

int n, m, x, y, z, d[NMAX], i, j;
vector < pair < int, int > > v[NMAX];
bool visited[NMAX];

struct comp
{
    bool operator () (pair < int, int > a, pair <int, int> b)
    {
        return a.second > b.second;
    }
};

priority_queue < pair < int, int >, vector < pair < int, int > >, comp > pq;

void dijkstra()
{
    for (i = 1; i <= n; ++ i)
        d[i] = inf;

    d[1] = 0;
    pq.push({1, 0});

    while (!pq.empty())
    {
        pair < int, int > curr = pq.top();
        pq.pop();

        if (!visited[curr.first])
        {
            visited[curr.first] = 1;

            for (auto &it : v[curr.first])
                if (!visited[it.first] && d[it.first] > d[curr.first] + it.second)
                {
                    d[it.first] = d[curr.first] + it.second;
                    pq.push({it.first, d[it.first]});
                }
        }
    }
}

int main()
{
    f >> n >> m;

    for (i = 1; i <= m; ++ i)
    {
        f >> x >> y >> z;
        v[x].push_back({y, z});
    }

    dijkstra();

    for (i = 2; i <= n; ++ i)
        if (d[i] == inf)
            g << -1 << " ";
        else
            g << d[i] << " ";
    return 0;
}