private bool CheckForNearlyLocatedDigits(int checkNumber, CheckType checkType)
{
var removed = false;
var digits = new List<List<int>>();
for (int i = 0; i < 9; i++)
{
digits.Add(new List<int>());
}
for (int i = 0; i < 9; i++)
{
var checkCell = Utility.GetCell(checkNumber, i, checkType, grid);
foreach (var digit in checkCell.MightBe)
{
digits[digit - 1].Add(i);
}
}
for (var i = 0; i < 9; i++)
{
var digit = digits[i];
var digitName = i + 1;
if (digit.Count > 1 && digit.Count <= 3)
{
var firstLocation = digit[0];
var firstRow = (int)Math.Floor(firstLocation / 3.0);
var firstCol = firstLocation % 3;
var rowLocated = true;
var colLocated = true;
foreach (var location in digit)
{
var row = (int)Math.Floor(location / 3.0);
if (row != firstRow)
{
rowLocated = false;
}
var col = location % 3;
if (col != firstCol)
{
colLocated = false;
}
}
if (rowLocated)
{
var globalRow = 3 * (int)Math.Floor(checkNumber / 3.0) + firstRow;
for (int j = 0; j < 9; j++)
{
var removeCell = Utility.GetCell(globalRow, j, CheckType.Row, grid);
var boxNum = Utility.GetBoxNum(removeCell);
if (boxNum != checkNumber && removeCell.MightBe.Contains(digitName) && removeCell.MightBe.Count > 1) {
removeCell.MightBe.Remove(digitName);
removed = true;
}
}
if (chatty && removed)
{
Console.WriteLine("In Box " + (checkNumber + 1) + ", " + digitName + " must be in Row " + (globalRow + 1));
}
}
if (colLocated)
{
var globalCol = 3 * (checkNumber % 3) + firstCol;
for (int j = 0; j < 9; j++)
{
var removeCell = Utility.GetCell(globalCol, j, CheckType.Column, grid);
var boxNum = Utility.GetBoxNum(removeCell);
if (boxNum != checkNumber && removeCell.MightBe.Contains(digitName) && removeCell.MightBe.Count > 1) {
removeCell.MightBe.Remove(digitName);
removed = true;
}
}
if (chatty && removed)
{
Console.WriteLine("In Box " + (checkNumber + 1) + ", " + digitName + " must be in Column " + (globalCol + 1));
}
}
}
}
return removed;
}
private bool CheckForIntersects(int checkNumber, CheckType checkType)
{
var removed = false;
for (int i = 0; i < 9; i++)
{
var basisCell = Utility.GetCell(checkNumber, i, checkType, grid);
var basisSet = basisCell.MightBe;
if (basisSet.Count == 1)
{
continue;
}
var intersects = new List<int> { };
var chattyRemoved = false;
for (int j = 0; j < 9; j++)
{
var checkCell = Utility.GetCell(checkNumber, j, checkType, grid);
if (j != i && basisSet.Intersect(checkCell.MightBe).Count() < checkCell.MightBe.Count && basisSet.Intersect(checkCell.MightBe).Count() > 0)
{
intersects.Add(j);
}
}
if (basisSet.Count == 2 && intersects.Count == 2 && checkType == CheckType.Box)
{
var intersect1 = Utility.GetCell(checkNumber, intersects[0], CheckType.Box, grid).MightBe;
var intersect2 = Utility.GetCell(checkNumber, intersects[1], CheckType.Box, grid).MightBe;
var union = Enumerable.Union(basisSet, Enumerable.Union(intersect1, intersect2));
if (union.Count() == intersects.Count + 1)
{
for (int k = 0; k < 9; k++)
{
if (k != i && !intersects.Contains(k))
{
var removeCell = Utility.GetCell(checkNumber, k, checkType, grid);
foreach (var digit in union)
{
if (removeCell.MightBe.Contains(digit))
{
removeCell.MightBe.Remove(digit);
if (removeCell.MightBe.Count == 0)
{
throw new Exception(checkType.ToString() + " " + (checkNumber + 1) + ": Intersect check ruled out all options for " + removeCell.Row + "," + removeCell.Column);
}
chattyRemoved = true;
removed = true;
}
}
}
}
}
if (chattyRemoved && chatty)
{
Console.WriteLine("In " + checkType.ToString() + " " + (checkNumber + 1) + ", the set " + string.Join(",", union) + " is covered by 3 cells");
}
}
}
return removed;
}