public static string Solve(string Board)
{
string[] leafNodesOfMoves = new string[] { Board };
while ((leafNodesOfMoves.Length > 0) && (leafNodesOfMoves[0].IndexOf(' ') != -1))
{
leafNodesOfMoves = (
from partialSolution in leafNodesOfMoves
let index = partialSolution.IndexOf(' ')
from numberToTry in Enumerable.Range(1, 9)
let searchLetter = numberToTry.ToString()[0]
let InvalidPositions =
from spaceToCheck in Enumerable.Range(0, 9)
let IsInRow = partialSolution[(int)Math.Floor(index / 9f) * 9 + spaceToCheck] == searchLetter
let IsInColumn = partialSolution[index % 9 + (spaceToCheck * 9)] == searchLetter
let IsInGroupBoxOf3x3 = partialSolution[(int)Math.Floor(index % 9f / 3) * 3 +
(int)Math.Floor(index / 27f) * 27 +
(int)Math.Floor(spaceToCheck / 3f) * 9 + spaceToCheck % 3] == searchLetter
where IsInRow || IsInColumn || IsInGroupBoxOf3x3
select spaceToCheck
where InvalidPositions.Count() == 0
select partialSolution.Substring(0, index) + searchLetter + partialSolution.Substring(index + 1)
).ToArray();
}
return((leafNodesOfMoves.Length == 0)
? "No solution"
: leafNodesOfMoves[0]);
}
public static string SolveStrings(string Board)
{
string[] leafNodesOfMoves = new string[] { Board };
while ((leafNodesOfMoves.Length > 0) && (leafNodesOfMoves[0].IndexOf(' ') != -1))
{
leafNodesOfMoves = (
from partialSolution in leafNodesOfMoves
let index = partialSolution.IndexOf(' ')
let column = index % 9
let groupOf3 = index - (index % 27) + column - (index % 3)
from searchLetter in "123456789"
let InvalidPositions =
from spaceToCheck in Enumerable.Range(0, 9)
let IsInRow = partialSolution[index - column + spaceToCheck] == searchLetter
let IsInColumn = partialSolution[column + (spaceToCheck * 9)] == searchLetter
let IsInGroupBoxOf3x3 = partialSolution[groupOf3 + (spaceToCheck % 3) +
(int)Math.Floor(spaceToCheck / 3f) * 9] == searchLetter
where IsInRow || IsInColumn || IsInGroupBoxOf3x3
select spaceToCheck
where InvalidPositions.Count() == 0
select partialSolution.Substring(0, index) + searchLetter + partialSolution.Substring(index + 1)
).ToArray();
}
return((leafNodesOfMoves.Length == 0)
? "No solution"
: leafNodesOfMoves[0]);
}
public void AddInvalidPosition(int position)
{
if (!InvalidPositions.Any(p => p == position))
{
InvalidPositions.Add(position);
}
}
