void dijkstra(int s)
{
dist.assign(n+1, INF);
dist[s] = 0LL;
par.assign(n+1, -1);
priority_queue <pp, vector <pp>, greater <pp> > PQ;
PQ.push(pp(dist[s], s));
while (!PQ.empty())
{
pp front = PQ.top();
PQ.pop();
long long int d = front.first;
int u = front.second;
if (d > dist[u])
continue;
for (int j = 0; j < (int)AdjList[u].size(); j++)
{
pp v = AdjList[u][j];
if (dist[v.first] > dist[u] + v.second)
{
dist[v.first] = dist[u] + v.second;
par[v.first] = u;
PQ.push(pp(dist[v.first], v.first));
}
}
}
}
