private Tuple <IIncrementableLine, int> FindSuitableDestinationLine(int sortingLineId, int slots)
{
// Get all other sorting lines that are not full, ordered
// by the Id closest to the id of the original line, with fewer
// cars into it
var lines = SortingLinesMap
.Where(kvp => !sortingLineId.Equals(kvp.Key.Id))
.Where(kvp => !kvp.Key.IsFull)
.OrderBy(kvp => Math.Abs(sortingLineId - kvp.Key.Id))
.OrderBy(kvp => kvp.Key.Count);
var notEnoughOpenSlots = lines.Sum(kvp => kvp.Key.OpenSlots) < slots;
// No suitable lines
if (!lines.Any() || notEnoughOpenSlots)
{
return(null);
}
// Return sorting line and how many cars should be moved to it
var line = lines.First().Key;
var amount = line.OpenSlots < slots ? line.OpenSlots : slots;
return(new Tuple <IIncrementableLine, int>(line, amount));
}
private Tuple <IDecrementableLine, int> GetReadyCars()
{
// Lines with a car to the correct destination on top (depth of a car is zero)
var lines = SortingLinesMap.Where(kvp => kvp.Value.Contains(0));
// No lines are ready
if (!lines.Any())
{
return(null);
}
// If multiple lines have cars with the correct destination on top, it
// does not matter which line will be selected
var line = lines.First();
// Count how many cars with the correct destination are in sequence on top
var depths = line.Value;
var amount = 1;
for (var i = 0; i < depths.Count - 1; i++)
{
// If the next car with the correct destination is not in sequence,
// stop counting
if (depths[i + 1] - depths[i] > 1)
{
break;
}
amount++;
}
// Return origin line and amount of cars ready to remove
return(new Tuple <IDecrementableLine, int>(line.Key, amount));
}
/// <summary>
/// Get an instruction to execute the next movement to remove
/// a car from the sorting line
/// </summary>
/// <returns>
/// A tuple where the first item is the origin line, the
/// second item is the destination line and the third item is the
/// number of cars that must be moved from the origin line
/// </returns>
public Tuple <IDecrementableLine, IIncrementableLine, int> GetInstruction()
{
// There are no cars to the correct destination in any sorting
// lines, return no instruction
if (!SortingLinesMap.Any(kvp => kvp.Value.Any()))
{
return(null);
}
// If there are cars on the top of a sorting line, move them to
// the train line
var readyCars = GetReadyCars();
if (readyCars != null)
{
return(new Tuple <IDecrementableLine, IIncrementableLine, int>(readyCars.Item1, TrainLine, readyCars.Item2));
}
// Order sorting lines by having a car to the correct destination
// closest to the top
var lines = SortingLinesMap.Where(kvp => kvp.Value.Any()).OrderBy(kvp => kvp.Value.FirstOrDefault());
// Work with the first sorting line
var line = lines.First();
// Depth is also the amount of cars to move out of the way
var amount = line.Value.First();
// Find closest sorting line with enough room
var destination = FindSuitableDestinationLine(line.Key.Id, amount);
// There is no suitable destination for any cars, return no instruction
if (destination == null)
{
return(null);
}
// Return instruction to move cars to a new sorting line
return(new Tuple <IDecrementableLine, IIncrementableLine, int>(line.Key, destination.Item1, destination.Item2));
}
