private List <JourneyStep> GetNextOptions(JourneyStep current, int caveDepth, int targetX, int targetY, HashSet <string> stepsCovered)
{
List <JourneyStep> options = new List <JourneyStep>();
int[] xMods = new[] { 0, 1, 0, -1 };
int[] yMods = new[] { -1, 0, 1, 0 };
for (int i = 0; i < 4; i++)
{
int x = current.X + xMods[i];
int y = current.Y + yMods[i];
if (x >= 0 && y >= 0)
{
int targetErosionLevel = CalculateErosionLevel(x, y, targetX, targetY, caveDepth);
string targetSoilType = DetermineType(targetErosionLevel);
List <int> targetEquipment = EquipmentAllowed(targetSoilType);
if (targetEquipment.Contains(current.Equipment) && stepsCovered.Add($"{x},{y},{current.Equipment}"))
{
JourneyStep newStep = new JourneyStep()
{
X = x,
Y = y,
Time = current.Time + 1,
Switching = 0,
Equipment = current.Equipment,
CurrentType = targetSoilType
};
options.Add(newStep);
}
}
// Add other allowed tool option
foreach (int otherTool in EquipmentAllowed(current.CurrentType))
{
if (otherTool != current.Equipment)
{
JourneyStep newStep = new JourneyStep()
{
X = current.X,
Y = current.Y,
Time = current.Time + 1,
Switching = 6,
Equipment = otherTool,
CurrentType = current.CurrentType
};
options.Add(newStep);
}
}
}
return(options);
}
public int FindBestTimeThroughCave(int caveDepth, int targetX, int targetY)
{
int bestTime = int.MaxValue;
// I struggled with this one because I wanted to use constructed strings instead of custom classes for the Hashset
// but then I did not separate the values in the strings with commas, so it was mismatching the values that overlapped
// This made me lose hours of work.
HashSet <string> stepsCovered = new HashSet <string>();
Queue <JourneyStep> queue = new Queue <JourneyStep>();
JourneyStep start = new JourneyStep()
{
X = 0,
Y = 0,
Time = 0,
Equipment = 2,
CurrentType = ".",
Switching = 0
};
queue.Enqueue(start);
stepsCovered.Add("0,0,2");
do
{
JourneyStep currentStep = queue.Dequeue();
// Handle switching
if (currentStep.Switching > 0)
{
if (currentStep.Switching != 1 ||
stepsCovered.Add($"{currentStep.X},{currentStep.Y},{currentStep.Equipment}"))
{
JourneyStep newStep = new JourneyStep()
{
X = currentStep.X,
Y = currentStep.Y,
Time = currentStep.Time + 1,
Switching = currentStep.Switching - 1,
Equipment = currentStep.Equipment,
CurrentType = currentStep.CurrentType
};
queue.Enqueue(newStep);
}
continue;
}
// If the currentStep time is > best time, then discard
if (currentStep.Time > bestTime)
{
continue;
}
// We have reached the target
if (currentStep.X == targetX && currentStep.Y == targetY)
{
int modTime = currentStep.Equipment == 2 ? currentStep.Time : currentStep.Time + 7;
if (modTime < bestTime)
{
bestTime = modTime;
}
break;
}
// Add next options
List <JourneyStep> options = GetNextOptions(currentStep, caveDepth, targetX, targetY, stepsCovered);
foreach (JourneyStep option in options)
{
queue.Enqueue(option);
}
} while (queue.Count > 0);
return(bestTime);
}