public void percolateDown(int i)
{
int x = heap[i];
while (left(i) < heap.size())
{
int child = right(i) < heap.size() && comp(heap[right(i)], heap[left(i)]) ? right(i) : left(i);
if (!comp(heap[child], x))
{
break;
}
heap[i] = heap[child];
indices[heap[i]] = i;
i = child;
}
heap [i] = x;
indices[x] = i;
}
public bool ok(int n)
{
return(n >= 0 && n < (int)indices.size());
}