public StockDelta(int pos, int val)
{
start = new StockNode { position = pos, value = val };
end = new StockNode { position = pos, value = val };
}
public StockDelta(List<int> list)
{
int count = list.Count;
start = new StockNode { position = 0, value = list[0] };
end = new StockNode { position = count, value = list[count-1] };
}