/// <summary>
/// To check if the puzzle is minimal or not.
/// </summary>
/// <param name="this">(<see langword="this"/> parameter) The puzzle to check.</param>
/// <returns>A <see cref="bool"/> value indicating that.</returns>
public static bool IsMinimal(this IReadOnlyGrid @this)
{
int hintCount = 0;
int[] array = @this.ToArray();
var valueList = new Queue <(int, int)>();
for (int i = 0; i < 9; i++)
{
for (int j = 0; j < 9; j++)
{
if (array[i * 9 + j] != 0)
{
hintCount++;
valueList.Enqueue((i, j));
}
}
}
int[][] tempArrays = new int[hintCount][];
for (int i = 0; i < hintCount; i++)
{
var(r, c) = valueList.Dequeue();
tempArrays[i] = (int[])array.Clone();
tempArrays[i][r * 9 + c] = 0;
}
var solver = new BitwiseSolver();
return(tempArrays.All(gridValues => !solver.Solve(Grid.CreateInstance(gridValues)).HasSolved));
}
