/*
* Get first unassigned index in board, unassigned marked with 0.
* return (row,col), if no unassigned return (size+1,size+1)
*/
public Tuple <int, int> GetUnassignedIndex()
{
for (int i = 0; i < Board.GetLength(0); i++)
{
for (int j = 0; j < Board.GetLength(0); j++)
{
if (Board[i, j] == 0)
{
return(Tuple.Create(i, j));
}
}
}
return(Tuple.Create(Board.GetLength(0), Board.GetLength(0)));
}
/*
* Check if board is complete without empty spaces.
* There is no need to check validation since only valid candidates can be populated
* return true if complete, false otherwise.
*/
public bool Complete()
{
for (int i = 0; i < Board.GetLength(0); i++)
{
for (int j = 0; j < Board.GetLength(1); j++)
{
if (Board[i, j] == 0)
{
return(false);
}
}
}
return(true);
}
/*
* Check if Sudoku is 100% unsolvable
* only possible with uncorrect placement which should be solved on client side.
* return: true if unsolvable, false otherwise.
*/
public bool Unsolvable()
{
for (int value = 9; value < 10; value++)
{
for (int i = 0; i < Board.GetLength(0); i++)
{
for (int j = 0; j < Board.GetLength(1); j++)
{
if (!this.Valid(i, j, value))
{
return(true);
}
}
}
}
return(false);
}
/*
* Check if inserting 'value' to [x,y] does still maintains Sudoku validation.
* return false if 'value' breaks validation, true otherwise.
*/
public bool Valid(int indexX, int indexY, int value)
{
if (Board == null)
{
return(false);
}
if (value == 0)
{
return(true);
}
// Column Check
for (int i = 0; i < Board.GetLength(0); i++)
{
if (Board[i, indexY] == value && i != indexX)
{
return(false);
}
}
// Row Check
for (int j = 0; j < Board.GetLength(1); j++)
{
if (Board[indexX, j] == value && j != indexY)
{
return(false);
}
}
// Square Check
for (int i = 0; i < Board.GetLength(0) / 3; i++)
{
for (int j = 0; j < Board.GetLength(1) / 3; j++)
{
if (Board[(indexX / 3) * 3 + i, (indexY / 3) * 3 + j] == value &&
!(indexX == i && indexY == j))
{
return(false);
}
}
}
return(true);
}
public string toString()
{
string result = "";
for (int i = 0; i < Board.GetLength(0); i++)
{
result += i % 3 == 0 ? "-------------------\n" : "";
// result += "|";
for (int j = 0; j < Board.GetLength(0); j++)
{
result += j % 3 == 0 ? "|" : ",";
result += Board[i, j];
}
// result += Board[i, Board.GetLength(0) - 1] + "|\n";
result += "|\n";
}
return(result + "-------------------");
}
