public IEnumerable <Island> Parse(IEnumerable <int> input)
{
var islands = new List <Island>();
var island = new Island();
foreach (var height in input)
{
var islandCell = new IslandCell(height);
if (CellIsLowerSeaLevel(islandCell))
{
if (!IslandIsUnderWater(island))
{
islands.Add(island);
}
island = new Island();
continue;
}
island.AddCell(islandCell);
}
islands.Add(island);
return(islands);
}
public int Execute(IEnumerable <Island> input)
{
var volume = 0;
foreach (var island in input)
{
var emptyIslandCell = new IslandCell(height: 0);
IslandCell currentCell = island.IslandCells.FirstOrDefault() ?? emptyIslandCell;
while (currentCell != emptyIslandCell)
{
var pool = GetPool(island, currentCell);
var poolVolume = GetPoolVolume(pool);
volume += poolVolume;
currentCell = pool.LastOrDefault() ?? emptyIslandCell;
}
}
return(volume);
}
private int GetPoolVolume(List <IslandCell> pool)
{
var poolVolume = 0;
var emptyCell = new IslandCell(height: 0);
var leftEdge = pool.FirstOrDefault() ?? emptyCell;
var rightEdge = pool.LastOrDefault() ?? emptyCell;
var minHeightEdge = Math.Min(leftEdge.Height, rightEdge.Height);
foreach (var currentCell in pool)
{
if (currentCell == leftEdge || currentCell == rightEdge)
{
continue;
}
var currentVolume = minHeightEdge - currentCell.Height;
poolVolume += currentVolume;
}
return(poolVolume);
}
private List <IslandCell> GetPool(Island island, IslandCell startCell)
{
var islandCells = GetCutIslandsCellsByStartCell(island.IslandCells, startCell);
var previewCell = islandCells.FirstOrDefault() ?? new IslandCell(height: 0);
var pool = new HashSet <IslandCell>();
var leftPoolEdgeFound = false;
var rightPoolEdgeFound = false;
foreach (var currentCell in islandCells)
{
if (rightPoolEdgeFound)
{
break;
}
if (leftPoolEdgeFound && previewCell.Height < currentCell.Height)
{
rightPoolEdgeFound = true;
pool.Add(previewCell);
pool.Add(currentCell);
}
if (!leftPoolEdgeFound && previewCell.Height > currentCell.Height)
{
leftPoolEdgeFound = true;
pool.Add(previewCell);
pool.Add(currentCell);
}
if (leftPoolEdgeFound)
{
pool.Add(currentCell);
}
previewCell = currentCell;
}
return(rightPoolEdgeFound && leftPoolEdgeFound?pool.ToList() : new List <IslandCell>());
}
private bool CellIsLowerSeaLevel(IslandCell islandCell)
{
return(islandCell.Height == 0);
}
private List <IslandCell> GetCutIslandsCellsByStartCell(List <IslandCell> islandCells, IslandCell startCell)
{
var startCellIndex = islandCells.IndexOf(startCell);
if (startCellIndex > -1)
{
islandCells = islandCells.ToList();
islandCells.RemoveRange(index: 0, count: startCellIndex);
}
else
{
islandCells = new List <IslandCell>();
}
return(islandCells);
}
