HackerRank: Dijkstra: Shortest Reach 2

#include <iostream>
#include <vector>
#include <queue>
#define ii pair<int, int>

using namespace std;

struct Arista
{
    int v, w;
};

struct Grafo
{
    vector <vector <Arista> > adj;
    vector <int> dist;

    void leer()
    {
        int n, m, a, b, w;
        cin >> n >> m;
        adj = vector <vector <Arista> > (n+1, vector <Arista> ());
        dist = vector <int> (n+1, 999999999);

        Arista edge, edge2;
        for(int i=0; i<m; i++)
        {
            cin >> a >> b >> w;
            edge.v = b;
            edge.w = w;
            adj[a].push_back(edge);

            edge2.v = a;
            edge2.w = w;
            adj[b].push_back(edge2);
        }
        int s;
        cin >> s;

        priority_queue<ii, vector <ii>, greater <ii> > pq;

        dist[s] = 0;
        pq.push(ii(0, s));

        while(pq.size())
        {
            ii p = pq.top();
            pq.pop();
            s = p.second;
            for(int i=0; i<adj[s].size(); i++)
            {
                if(dist[s]+adj[s][i].w < dist[adj[s][i].v])
                {
                    dist[adj[s][i].v] = dist[s]+adj[s][i].w;
                    pq.push(ii(dist[adj[s][i].v], adj[s][i].v));
                }
            }
        }

        for(int i=1; i<dist.size(); i++)
        {
            if(dist[i] == 999999999)
                cout << -1 << " ";
            else if(dist[i])
                cout << dist[i] << " ";
        }

        cout << endl;

    }

};

int main()
{
    int tc;
    cin >> tc;
    while(tc--)
    {
        Grafo g;
        g.leer();
    }
    return 0;
}