private void Relax(DirectedWeightedEdge edge, int target)
{
var u = edge.To();
var v = edge.From();
if (distTo[u] > distTo[v] + edge.Weight())
{
distTo[u] = distTo[v] + edge.Weight();
edgeTo[u] = edge;
if (pq.Contains(u))
{
pq.DecreaseKey(u, heuristic(target, u) + distTo[u]);
}
else
{
pq.Insert(u, heuristic(target, u) + distTo[u]);
}
}
}