internal void TransferTo(Bucket targetBucket)
{
uint diff = CurrentVolume > targetBucket.RemainingVolume ? CurrentVolume - targetBucket.RemainingVolume : 0;
targetBucket.Transfer(CurrentVolume);
CurrentVolume = diff;
}
public PuzzleResult GetShortestSolution(Bucket sourceBucket, Bucket targetBucket, uint goal)
{
ValidateInput(sourceBucket, targetBucket, goal);
var sourceSolution = Solve(sourceBucket, targetBucket, goal);
var targetSolution = Solve(targetBucket, sourceBucket, goal);
return FindShortestSolution(sourceSolution, targetSolution);
}
public PuzzleResult Solve(Bucket sourceBucket, Bucket targetBucket, uint goal)
{
var result = Factory.CreatePuzzleResult();
ValidateInput(sourceBucket, targetBucket, goal);
//if (!HasSolution(sourceBucket, targetBucket, goal))
//{
// return result;
//}
sourceBucket.Empty();
targetBucket.Empty();
result.AddStep(Factory.CreatePuzzleSolutionStep("E", sourceBucket.CurrentVolume, "E", targetBucket.CurrentVolume));
do
{
if (sourceBucket.IsEmpty())
{
sourceBucket.Fill();
result.AddStep(Factory.CreatePuzzleSolutionStep("F", sourceBucket.CurrentVolume, "N", targetBucket.CurrentVolume));
}
else if (targetBucket.IsFull())
{
if (sourceBucket.IsFull()) // No solution!
{
result = Factory.CreatePuzzleResult(); // Indicate that there's no solution
break;
}
targetBucket.Empty();
result.AddStep(Factory.CreatePuzzleSolutionStep("N", sourceBucket.CurrentVolume, "E", targetBucket.CurrentVolume));
}
else
{
sourceBucket.TransferTo(targetBucket);
result.AddStep(Factory.CreatePuzzleSolutionStep("T", sourceBucket.CurrentVolume, "T", targetBucket.CurrentVolume));
}
}
while (targetBucket.CurrentVolume != goal && sourceBucket.CurrentVolume != goal);
return result;
}
private static bool HasSolution(Bucket sourceBucket, Bucket targetBucket, uint goal)
{
bool hasSolution = true;
// Validation rule: source bucket and target bucket cannot have the same capacity
if (sourceBucket.Capacity == targetBucket.Capacity)
{
hasSolution = false;
}
var sourceEven = sourceBucket.Capacity % 2 == 0;
var targetEven = targetBucket.Capacity % 2 == 0;
var goalOdd = goal % 2 == 0;
// short cuircuit in case of even buycket sizes and odd goal
if (sourceEven && targetEven && goalOdd)
{
hasSolution = false;
}
return hasSolution;
}
private static void ValidateInput(Bucket sourceBucket, Bucket targetBucket, uint goal)
{
var largerBucketSize = sourceBucket.Capacity > targetBucket.Capacity ? sourceBucket.Capacity : targetBucket.Capacity;
// Validation rule: goal amount (X) should be less than largest bucket size
if (goal > largerBucketSize)
{
throw new LakePuzzleException(string.Format("goal({0}) cannot be greater than largest bucket size({1})", goal, largerBucketSize));
}
}