/// <summary>
/// Checks if a given SudokuEntry is valid for the current sudoku.
/// </summary>
/// <param name="sudokuEntry">The SudokuEntry that we want to check.</param>
/// <returns>True if the given SudokuEntry is valid for the current sudoku, otherwise false.</returns>
private bool EntryIsValid(SudokuEntry sudokuEntry)
{
foreach (SudokuEntry entry in Entries)
{
// First, we check if there is a SudokuEntry with the same value as sudokuEntry in the same block, column or row as sudokuEntry.
// If there is, sudokuEntry is invalid, so we return false.
if (entry.Value == sudokuEntry.Value)
{
if (entry.BlockIndex == sudokuEntry.BlockIndex)
{
return(false);
}
if (entry.ColumnIndex == sudokuEntry.ColumnIndex)
{
return(false);
}
if (entry.RowIndex == sudokuEntry.RowIndex)
{
return(false);
}
}
// Second, we check whether there already is a SudokuEntry at the same location as sudokuEntry
// and if there is, and it's locked, sudokuEntry is also invalid, so we return false.
if (entry.ColumnIndex == sudokuEntry.ColumnIndex && entry.RowIndex == sudokuEntry.RowIndex && entry.Locked)
{
return(false);
}
}
return(true);
}
/// <summary>
/// Checks whether a SudokuEntry is locked or not.
/// </summary>
/// <param name="columnIndex">The columnIndex of the SudokuEntry that we want to check.</param>
/// <param name="rowIndex">The rowIndex of the SudokuEntry that we want to check.</param>
/// <returns>True if the SudokuEntry for the given rowIndex and columnIndex is locked, otherwise false.</returns>
public bool EntryIsLocked(int columnIndex, int rowIndex)
{
SudokuEntry sudokuEntry = FindEntry(columnIndex, rowIndex);
// If there isn't a SudokuEntry for the specified rowIndex and columnIndex, it çan't be locked.
if (sudokuEntry == null || sudokuEntry.Locked == false)
{
return(false);
}
else
{
return(true);
}
}
/// <summary>
/// Removes a SudokuEntry from the 'Entries' list.
/// </summary>
/// <param name="columnIndex">The columnIndex of the SudokuEntry that needs to be removed.</param>
/// <param name="rowIndex">The rowIndex of the SudokuEntry that needs to be removed.</param>
/// <returns>True if the SudokuEntry was removed successfully, otherwise false.</returns>
public bool RemoveEntry(int columnIndex, int rowIndex)
{
SudokuEntry sudokuEntry = FindEntry(columnIndex, rowIndex);
// If there isn't a SudokuEntry for the specified rowIndex and columnIndex,
// or the found SudokuEntry is locked, we can't remove it, so return false.
if (sudokuEntry == null || sudokuEntry.Locked)
{
return(false);
}
else
{
Entries.Remove(sudokuEntry);
return(true);
}
}
/// <summary>
/// Solve the sudoku.
/// </summary>
/// <param name="sudokuViewer">The current ViewerForm instance.</param>
public void Solve(ViewerForm sudokuViewer)
{
// Here 'i' represents the columnIndex, while 'i2' respresents the rowIndex.
for (int i = 0; i < GridSize; i++)
{
for (int i2 = 0; i2 < GridSize; i2++)
{
int blockIndex = Convert.ToInt32((Math.Floor((double)(i / BlockSize.Horizontal))) +
((Math.Floor((double)(i2 / BlockSize.Vertical))) * (GridSize / BlockSize.Horizontal)));
SudokuEntry currentEntry = EntriesList.FindEntry(i, i2);
// If there isn't a SudokuEntry at this location yet, set current value to 0.
int value = currentEntry == null ? 0 : currentEntry.Value;
// If the SudokuEntry at this location is locked, continue to the next location by incrementing the inner for-loop.
if (currentEntry != null && currentEntry.Locked)
{
continue;
}
// If there already is a SudokuEntry at this location, which is unlocked, remove it from the 'EntriesList'
// so we don't end up with multiple instances of SudokuEntry for the same location.
if (value > 0)
{
EntriesList.RemoveEntry(i, i2);
}
// Here we increment 'value' so we don't end up in an endless loop where Solve() constantly finds the same value for the same location
// after backtracking.
if (Solve((value + 1), blockIndex, i, i2) == false)
{
// If we couldn't find a valid value for this location, backtrack.
int[] vars = DetermineNext(i, i2);
i = vars[0];
i2 = vars[1];
}
// Update the progress bar to reflect current progress.
(sudokuViewer.Controls[1] as ProgressBar).Value = (int)Math.Round((100d / ((double)GridSize * (double)GridSize)) * ((double)(i + 1) * (double)(GridSize)));
}
}
// Set the progress bar to 100% when we are finished, to account for the user entering a sudoku
// where the final column is already completely solved.
(sudokuViewer.Controls[1] as ProgressBar).Value = 100;
}
/// <summary>
/// Adds a new SudokuEntry to the 'Entries' list, provided the new SudokuEntry is valid for the current sudoku.
/// </summary>
/// <param name="value">The 'value' the new SudokuEntry should take.</param>
/// <param name="blockIndex">The 'blockIndex' for the new SudokuEntry.</param>
/// <param name="columnIndex">The 'columnIndex' for the new SudokuEntry.</param>
/// <param name="rowIndex">The 'rowIndex' for the new SudokuEntry.</param>
/// <param name="initialRead">
/// Is true when the SudokuEntry is being added through Sudoku.ReadEntries(),
/// which means that the value for this SudokuEntry was added by the user, so it should be locked.
/// </param>
/// <returns>True if the new SudokuEntry is valid and was added successfully, otherwise false.</returns>
public bool AddEntry(int value, int blockIndex, int columnIndex, int rowIndex, bool initialRead)
{
// A value in a sudoku must always be >=1, so a value of 0 is invalid.
if (value == 0)
{
return(false);
}
SudokuEntry sudokuEntry = new SudokuEntry(value, blockIndex, rowIndex, columnIndex, initialRead);
// If sudokuEntry is valid for the current sudoku, add it to the 'Entries' list and return true, otherwise return false.
if (EntryIsValid(sudokuEntry))
{
Entries.Add(sudokuEntry);
return(true);
}
else
{
return(false);
}
}