public static Grid Minimize(Grid grid)
{
IList removeCandidates = new ArrayList();
for (int cellNumber = 0; cellNumber < 81; cellNumber++)
{
int row = cellNumber / 9;
int column = cellNumber % 9;
if (grid.cells[row, column] != 0)
{
removeCandidates.Add(cellNumber);
}
}
while (removeCandidates.Count > 0)
{
int removeIndex = random.Next(removeCandidates.Count);
int removeCellNumber = (int)removeCandidates[removeIndex];
int row = removeCellNumber / 9;
int column = removeCellNumber % 9;
int value = grid.cells[row, column];
grid.cells[row, column] = 0;
if (!ValidNumberPlace(grid))
{
grid.cells[row, column] = value;
}
else
{
//return Minimize(grid);
}
removeCandidates.RemoveAt(removeIndex);
}
return grid;
}
public static Grid Solve(Grid grid)
{
IList solutions = Solve((Grid)grid.Clone(), 1);
if (solutions.Count == 0)
{
return null;
}
else
{
return (Grid)solutions[0];
}
}
public object Clone()
{
Grid clone = new Grid(this.BlocksAcross);
for (int row = 0; row < cellsInRow; row++)
{
for (int column = 0; column < cellsInRow; column++)
{
clone.cells[row, column] = cells[row, column];
}
}
return clone;
}
public static bool ValidNumberPlace(Grid grid)
{
// Check only one solution exists
IList solutions = Solve((Grid)grid.Clone(), 2);
if (solutions.Count == 1)
{
return true;
}
// Either unsolvable or multiple solutions
return false;
}
public static bool CheckMinimality(Grid grid)
{
Grid temp = (Grid)grid.Clone();
for (int row = 0; row < temp.CellsInRow; row++)
{
for (int column = 0; column < temp.CellsInRow; column++)
{
if (temp.cells[row, column] != 0)
{
int value = temp.cells[row, column];
temp.cells[row, column] = 0;
if (ValidNumberPlace(temp))
{
return false;
}
temp.cells[row, column] = value;
}
}
}
return true;
}
public static Grid FillOutCells(Grid grid, Grid solution, int number)
{
for (; number > 0; number--)
{
int candidateIndex = random.Next(81 - grid.CountFilledCells());
int m = -1, i = 0, j = 0;
for (i = 0; i < 9 && m < candidateIndex; i++)
{
for (j = 0; j < 9 && m < candidateIndex; j++)
{
if (grid.cells[i, j] == 0)
{
m++;
if (m == candidateIndex)
{
grid.cells[i, j] = solution.cells[i, j];
}
}
}
}
}
return grid;
}
public static bool FindCandidateInBox(Grid grid, int row, int col, int Num)
{
int firstRow = (row / 3) * 3;
int firstCol = (col / 3) * 3;
for (int i = 0; i < 3; i++)
{
for (int j = 0; j < 3; j++)
{
if (grid.IsCellEmpty(firstRow + i, firstCol + j) &&
grid.Possibilities(firstRow + i, firstCol + j).Contains(Num) &&
!(firstRow + i != row || firstCol + j != col))
{
return true;
}
}
}
return false;
}
public static bool FindCandidateInCol(Grid grid, int row, int col, int Num)
{
for (int i = 0; i < grid.CellsInRow; i++)
{
if (grid.IsCellEmpty(i, col) && i != row && grid.Possibilities(i, col).Contains(Num))
{
return true;
}
}
return false;
}
/// <summary>
/// Find all Unique Candidates in grid
/// and fill out the uniqueCandidates Array in the grid
/// </summary>
/// <param name="grid">Grid</param>
/// <returns>the number of Unique Candidates</returns>
public static int FindUniqueCandidates(Grid grid)
{
// Grid grid = (Grid)gridOrg.Clone();
grid.resetUniqueCandidates();
nodes = 0;
int uniquesCand = 0;
unsolvableCell = false;
//find Unique Candidates in rows
for (int searchRow = 0; searchRow < grid.CellsInRow; searchRow++)
{
for (int searchCol = 0; searchCol < grid.CellsInRow; searchCol++)
{
if (!grid.IsCellEmpty(searchRow, searchCol))
{
continue;
}
IList candidates = grid.Possibilities(searchRow, searchCol);
IList candidates2 = new ArrayList(candidates);
if (candidates.Count > 1)
{
for (int cand = 0; cand < candidates.Count; cand++)
{
if (FindCandidateInRow(grid, searchRow, searchCol, (int)candidates[cand]))
{
candidates2.Remove(candidates[cand]);
}
}
}
if (candidates2.Count == 1)
{
grid.uniqueCandidates[searchRow, searchCol] = (int)candidates2[0];
}
}
}
//find Unique Candidates in colums
for (int searchCol = 0; searchCol < grid.CellsInRow; searchCol++)
{
for (int searchRow = 0; searchRow < grid.CellsInRow; searchRow++)
{
if (!grid.IsCellEmpty(searchRow, searchCol))
{
continue;
}
IList candidates = grid.Possibilities(searchRow, searchCol);
IList candidates2 = new ArrayList(candidates);
if (candidates.Count > 1)
{
for (int cand = 0; cand < candidates.Count; cand++)
{
if (FindCandidateInCol(grid, searchRow, searchCol, (int)candidates[cand]))
{
candidates2.Remove(candidates[cand]);
}
}
}
if (candidates2.Count == 1)
{
grid.uniqueCandidates[searchRow, searchCol] = (int)candidates2[0];
}
}
}
//find Unique Candidates in boxes
for (int searchRow = 0; searchRow < grid.CellsInRow; searchRow++)
{
for (int searchCol = 0; searchCol < grid.CellsInRow; searchCol++)
{
if (!grid.IsCellEmpty(searchRow, searchCol))
{
continue;
}
IList candidates = grid.Possibilities(searchRow, searchCol);
IList candidates2 = new ArrayList(candidates);
if (candidates.Count > 1)
{
for (int cand = 0; cand < candidates.Count; cand++)
{
if (FindCandidateInBox(grid, searchRow, searchCol, (int)candidates[cand]))
{
candidates2.Remove(candidates[cand]);
}
}
}
else
{
if (candidates.Count == 1)
{
uniquesCand++;
}
else
{
unsolvableCell = true;
}
}
if (candidates2.Count == 1)
{
grid.uniqueCandidates[searchRow, searchCol] = (int)candidates2[0];
}
}
}
for (int i = 0; i < 9; i++)
{
for (int j = 0; j < 9; j++)
{
if (grid.uniqueCandidates[i, j] != 0)
{
nodes++;
}
}
}
nodes = nodes + (uniquesCand / 2);
return nodes;
}
/// <summary>
/// rate a grid
/// returns it as int
/// the lower the harder
/// </summary>
/// <param name="grid">Grid</param>
/// <returns></returns>
public static int Rate(Grid gridOrg)
{
Grid grid = (Grid)gridOrg.Clone();
int rate = 0;
rateAll = 0;
// for(int trys = 0; trys<10;trys++)
// {
// grid = (Grid)gridOrg.Clone();
// rate = 0;
while (grid.CountFilledCells() < (grid.CellsInRow * grid.CellsInRow))
{
int cand = FindUniqueCandidates(grid);
rate += cand;
if (cand > 0)
{
int candidateIndex = random.Next(cand);
int m = -1, i = 0, j = 0, candidateRow = 0, candidateCol = 0;
for (i = 0; i < 9 && m < candidateIndex; i++)
{
for (j = 0; j < 9 && m < candidateIndex; j++)
{
if (grid.uniqueCandidates[i, j] != 0)
{
m++;
if (m == candidateIndex)
{
candidateRow = i;
candidateCol = j;
}
}
}
}
grid.cells[candidateRow, candidateCol] = grid.uniqueCandidates[candidateRow, candidateCol];
}
else
{
//rate = rate - ((grid.BlocksAcross * grid.BlocksAcross) - grid.CountFilledCells());
//no more unique cells -> difficult grid
rate = grid.CountFilledCells();
break;
}
}
// rateAll += rate;
// MediaPortal.GUI.Library.Log.WriteFile(MediaPortal.GUI.Library.LogType.Log, "Soduko Rate end "+trys+" notes: {0}", rate);
// }
return rate;
}
/// <summary>
/// Solve given sudoku grid and solutions upto maximum number specified
/// </summary>
/// <param name="g"></param>
/// <returns></returns>
public static IList Solve(Grid grid, int maxSolutions)
{
ArrayList solutions = new ArrayList();
// If grid is solved then return as solution
if (grid.CountFilledCells() == (grid.CellsInRow * grid.CellsInRow))
{
solutions.Add(grid.Clone());
return solutions;
}
// Solve singles
//Singles(grid);
// Choose unsolved cell
int leastCandidatesRow = -1;
int leastCandidatesColumn = -1;
IList leastCandidates = null;
for (int row = 0; row < grid.CellsInRow; row++)
{
for (int column = 0; column < grid.CellsInRow; column++)
{
if (grid.cells[row, column] == 0)
{
IList candidates = grid.Possibilities(row, column);
// If cell has no possible value then grid is not solvable so quit now
if (candidates.Count == 0)
{
return solutions;
}
else if (leastCandidates == null || leastCandidates.Count > candidates.Count)
{
leastCandidatesRow = row;
leastCandidatesColumn = column;
leastCandidates = candidates;
}
}
}
}
// For all candidates of unsolved cell
if (leastCandidates != null)
{
while (leastCandidates.Count > 0)
{
// Set candidate
int candidateIndex = random.Next(leastCandidates.Count);
grid.cells[leastCandidatesRow, leastCandidatesColumn] = (int)leastCandidates[candidateIndex];
leastCandidates.RemoveAt(candidateIndex);
Grid nextLevelGrid = (Grid)grid.Clone();
IList nextLevelSolutions = Solve(nextLevelGrid, maxSolutions);
solutions.AddRange(nextLevelSolutions);
// Trim number of solutions so we don't exceed maximum required
if (solutions.Count > maxSolutions)
{
solutions.RemoveRange(0, solutions.Count - maxSolutions);
}
if (solutions.Count == maxSolutions)
{
return solutions;
}
}
}
return solutions;
}
public void HiddenSingles(Grid grid)
{
// First try rows
for (int row = 0; row < grid.CellsInRow; row++)
{
int[] hiddenSingles = new int[grid.CellsInRow];
for (int value = 0; value < grid.CellsInRow; value++)
{
hiddenSingles[value] = -1;
}
// Now get possibilities for all cells
for (int column = 0; column < grid.CellsInRow; column++)
{
IList candidates = grid.Possibilities(row, column);
foreach (int candidate in candidates)
{
if (hiddenSingles[candidate - 1] == -1)
{
hiddenSingles[candidate - 1] = column;
}
else
{
hiddenSingles[candidate - 1] = grid.CellsInRow;
}
}
}
for (int value = 0; value < grid.CellsInRow; value++)
{
if (hiddenSingles[value] >= 0 && hiddenSingles[value] < grid.CellsInRow)
{
// Got a hidden single
grid.cells[row, hiddenSingles[value]] = value;
}
}
}
}
/// <summary>
/// Apply singles strategy to supplied grid as much as possible
/// </summary>
/// <param name="grid"></param>
public static void Singles(Grid grid)
{
int row = 0;
int column = 0;
while (row < grid.CellsInRow)
{
while (column < grid.CellsInRow)
{
if (grid.cells[row, column] == 0)
{
IList candidates = grid.Possibilities(row, column);
if (candidates.Count == 1)
{
grid.cells[row, column] = (int)candidates[0];
// Restart search from top left
row = 0;
column = 0;
}
else
{
column++;
}
}
else
{
column++;
}
}
row++;
}
}
public static Grid Generate(int blocksAcross)
{
// First generate a random completed grid that is valid
Grid empty = new Grid(blocksAcross);
Grid solution = Solve(empty);
Grid puzzle = (Grid)solution.Clone();
return Minimize(puzzle);
/*
Random random = new Random(DateTime.Now.Millisecond);
IList removeCandidates = new ArrayList();
for (int cellNumber = 1; cellNumber <= 81; cellNumber++)
{
removeCandidates.Add(cellNumber);
}
while (removeCandidates.Count > 0)
{
int removeIndex = random.Next(removeCandidates.Count);
int row = removeIndex / puzzle.CellsInRow;
int column = removeIndex % puzzle.CellsInRow;
if (puzzle.cells[row, column] != 0)
{
int value = puzzle.cells[row, column];
puzzle.cells[row, column] = 0;
IList solutions = Solve((Grid)puzzle.Clone(), 2);
if (solutions.Count == 2 || solutions.Count == 0)
{
puzzle.cells[row, column] = value;
}
else
{
cellsRemoved;
}
}
}
IList solns = Solve((Grid)puzzle.Clone(), 10);
return puzzle;
*/
}