public static bool IsMinimal(this Grid grid)
{
Contract.Assume(!(grid is null));
int hintCount = 0;
var array = grid.ToArray();
var valueList = new Queue <(int, int)>();
for (int i = 0; i < 9; i++)
{
for (int j = 0; j < 9; j++)
{
if (array[i, j] != 0)
{
hintCount++;
valueList.Enqueue((i, j));
}
}
}
var tempArrays = new int[hintCount][, ];
for (int i = 0; i < hintCount; i++)
{
var(r, c) = valueList.Dequeue();
tempArrays[i] = (int[, ])array.Clone();
tempArrays[i][r, c] = 0;
}
var solver = new DancingLinksSolver();
return(tempArrays.All(gridArray => solver.Solve(gridArray, out _) is null));
}
public static bool IsUnique(this Grid grid, [NotNullWhen(true)] out Grid?resultIfUnique)
{
try
{
var result = new DancingLinksSolver().Solve(grid, out _);
resultIfUnique = result;
return(!(result is null));
}
catch
{
resultIfUnique = default;
return(false);
}
}