public static WaitingArea ParseInputLines(IList <string> inputLines)
{
int width = inputLines.Count > 0 ? inputLines[0].Length : 0;
int height = inputLines.Count;
var gridCellTypes = new Dictionary <GridPoint, CellType>();
for (int row = 0; row < inputLines.Count; row++)
{
var inputLine = inputLines[row];
for (int column = 0; column < inputLine.Length; column++)
{
var cellType = CellType.Floor;
var cellDefinition = inputLine[column].ToString();
if ("L".Equals(cellDefinition))
{
cellType = CellType.ChairOpen;
}
else if ("#".Equals(cellDefinition))
{
cellType = CellType.ChairOccupied;
}
var point = new GridPoint(column, row);
gridCellTypes.Add(point, cellType);
}
}
var result = new WaitingArea(width, height, gridCellTypes);
return(result);
}
public static WaitingArea EvolveWaitingAreaUntilSteadyState(
WaitingArea initialWaitingArea,
EvolutionRules evolutionRules)
{
WaitingArea previousState = null;
var nextState = initialWaitingArea;
while (!nextState.Equals(previousState))
{
previousState = nextState;
nextState = GetNextWaitingAreaState(previousState, evolutionRules);
}
return(previousState);
}
public static int GetNumberOfSeenOccupiedSeats(
WaitingArea waitingArea,
GridPoint point,
bool onlyConsiderAdjacentCells)
{
int result = 0;
// Find seen seats along 8 directional rays
var raySlopes = new List <Tuple <int, int> >()
{
new Tuple <int, int>(-1, -1),
new Tuple <int, int>(0, -1),
new Tuple <int, int>(1, -1),
new Tuple <int, int>(-1, 0),
new Tuple <int, int>(1, 0),
new Tuple <int, int>(-1, 1),
new Tuple <int, int>(0, 1),
new Tuple <int, int>(1, 1)
};
foreach (var raySlope in raySlopes)
{
var nextPoint = new GridPoint(point.X + raySlope.Item1, point.Y + raySlope.Item2);
while (waitingArea.GridCellTypes.ContainsKey(nextPoint))
{
if (CellType.ChairOccupied.Equals(waitingArea.GridCellTypes[nextPoint]))
{
result++;
break;
}
else if (CellType.ChairOpen.Equals(waitingArea.GridCellTypes[nextPoint]))
{
break;
}
if (onlyConsiderAdjacentCells)
{
break;
}
nextPoint = new GridPoint(nextPoint.X + raySlope.Item1, nextPoint.Y + raySlope.Item2);
}
}
return(result);
}
public static WaitingArea GetNextWaitingAreaState(
WaitingArea waitingArea,
EvolutionRules evolutionRules)
{
// For each cell:
// If a seat is empty (L) and there are no occupied seats adjacent to it, the seat becomes occupied.
// If a seat is occupied(#) and four or more seats adjacent to it are also occupied, the seat becomes empty.
// Otherwise, the seat's state does not change.
// Floor(.) never changes; seats don't move, and nobody sits on the floor.
var updatedGridCellTypes = new Dictionary <GridPoint, CellType>();
for (int row = 0; row < waitingArea.Height; row++)
{
for (int column = 0; column < waitingArea.Width; column++)
{
var point = new GridPoint(column, row);
var cellType = CellType.Floor;
if (waitingArea.GridCellTypes.ContainsKey(point))
{
cellType = waitingArea.GridCellTypes[point];
}
if (CellType.Floor.Equals(cellType))
{
updatedGridCellTypes.Add(point, cellType);
continue;
}
int numberOfAdjacentOccupiedSeats = GetNumberOfSeenOccupiedSeats(waitingArea, point, evolutionRules.OnlyConsiderAdjacentCells);
if (CellType.ChairOpen.Equals(cellType) && numberOfAdjacentOccupiedSeats == 0)
{
cellType = CellType.ChairOccupied;
}
else if (CellType.ChairOccupied.Equals(cellType) && numberOfAdjacentOccupiedSeats >= evolutionRules.MinimumNumberOfSeenOccupiedSeatsToFlipToEmpty)
{
cellType = CellType.ChairOpen;
}
updatedGridCellTypes.Add(point, cellType);
}
}
var result = new WaitingArea(waitingArea.Width, waitingArea.Width, updatedGridCellTypes);
return(result);
}
// Equals, GetHashCode, and ToString() adapted from Microsoft example here:
// https://docs.microsoft.com/en-us/dotnet/api/system.object.equals?view=netcore-3.1
public override bool Equals(Object obj)
{
//Check for null and compare run-time types.
if ((obj == null) || !this.GetType().Equals(obj.GetType()))
{
return(false);
}
else
{
WaitingArea other = (WaitingArea)obj;
if (Width != other.Width)
{
return(false);
}
if (Height != other.Height)
{
return(false);
}
return(GridCellTypes.Count == other.GridCellTypes.Count &&
!GridCellTypes.Except(other.GridCellTypes).Any());
}
}