private void Fetch(uint value, SimpleList <int> intersection, SudokuRegion intersected, SudokuState state, ICollection <IEvent> events)
{
IEvent result = NoReduction.Instance;
var mask = ~value;
foreach (var index in intersected)
{
// items in the shared section should be skipped.
if (intersection.Contains(index))
{
continue;
}
var test = state.And <ReducePointingPairs>(index, mask);
if (test is ValueFound)
{
events.Add(test);
}
else if (test is ReducedOption)
{
result = test;
}
}
if (result is ReducedOption)
{
events.Add(ReducedOptions.Ctor <ReduceNakedPairs>());
}
}
private void ReduceRegion(int skip, SudokuRegion region, SudokuState state, ICollection <IEvent> events)
{
var quad = 0u;
buffer.Clear();
foreach (var index in region.Skip(skip))
{
var value = state[index];
if (SudokuCell.Count(value) < 4)
{
quad |= value;
// Joined the represent more then 3 values.
if (SudokuCell.Count(quad) > 4 || buffer.Count > 3)
{
return;
}
buffer.Add(index);
}
}
if (buffer.Count == 4)
{
Fetch(quad, buffer, region, state, events);
}
}
private void Fetch(uint quad, SimpleList <int> buffer, SudokuRegion region, SudokuState state, ICollection <IEvent> events)
{
var reduced = false;
var mask = ~quad;
foreach (var index in region)
{
if (buffer.Contains(index))
{
continue;
}
var result = state.And <ReduceNakedTriples>(index, mask);
if (result is ValueFound)
{
events.Add(result);
}
else if (result is ReducedOption)
{
reduced = true;
}
}
if (reduced)
{
events.Add(ReducedOptions.Ctor <ReduceNakedTriples>());
}
}
private void Fetch(uint nakedPair, SudokuRegion region, SudokuState state, ICollection <IEvent> events)
{
IEvent result = NoReduction.Instance;
var mask = ~nakedPair;
foreach (var index in region)
{
var value = state[index];
if (value != nakedPair)
{
var test = state.And <ReduceNakedPairs>(index, mask);
if (test is ValueFound)
{
events.Add(test);
}
else if (test is ReducedOption)
{
result = test;
}
}
}
if (result is ReducedOption)
{
events.Add(ReducedOptions.Ctor <ReduceNakedPairs>());
}
}
private void ReduceRegion(uint pair, SudokuRegion region, SudokuState state, ICollection <IEvent> events)
{
HiddenPairs.Clear();
foreach (var index in region)
{
var and = state[index] & pair;
// at least on of the two is pressent.
if (and != 0)
{
// If not both are present or we already had 2, return.
if (and != pair || HiddenPairs.Count > 1)
{
return;
}
HiddenPairs.Add(index);
}
}
if (HiddenPairs.Count == 2)
{
Fetch(pair, HiddenPairs, state, events);
}
}
private void ReduceRegion(SudokuRegion region, SudokuState state, ICollection <IEvent> events)
{
var nakedPair = 0u;
var count = 0;
foreach (var index in region)
{
var value = state[index];
// nothing found yet.
if (nakedPair == default)
{
if (SudokuCell.Count(value) == 2)
{
nakedPair = value;
count++;
}
}
// Equal to the first (potential) naked pair.
else if (value == nakedPair && count++ > 2)
{
throw new InvalidPuzzleException();
}
}
if (count > 1)
{
Fetch(nakedPair, region, state, events);
}
}
private void CheckCells(SudokuState state, SudokuRegion region, uint singleValue, ICollection <IEvent> events)
{
var hidden = NoIndex;
foreach (var index in region)
{
var value = state[index];
// the cell has the value.
if ((singleValue & value) != 0)
{
// Already value, try next.
if (singleValue == value)
{
return;
}
// not the first
if (hidden != NoIndex)
{
return;
}
hidden = index;
}
}
if (hidden == NoIndex)
{
return;
}
events.Add(state.And <ReduceHiddenSingles>(hidden, singleValue));
}
/// <summary>Initializes all column regions.</summary>
private void InitializeColumnRegions(int size2)
{
for (var column = 0; column < size2; column++)
{
var region = new SudokuRegion(SudokuRegionType.Column);
Regions.Add(region);
for (var height = 0; height < size2; height++)
{
region.Add(Grid[height, column]);
}
}
}
/// <summary>Initializes all row regions.</summary>
private void InitializeRowRegions(int size2)
{
for (int row = 0; row < size2; row++)
{
var region = new SudokuRegion(SudokuRegionType.Row);
Regions.Add(region);
for (int width = 0; width < size2; width++)
{
region.Add(Grid[row, width]);
}
}
}
public void Solve(uint value, SudokuRegion first, SudokuRegion second, SudokuRegionType otherType, SudokuState state, ICollection <IEvent> events)
{
buffer.Clear();
for (var index = 0; index < 9; index++)
{
var indexFirst = first[index];
var indexSecond = second[index];
var joinFirst = state[indexFirst] & value;
var joinSecond = state[indexSecond] & value;
if (joinFirst == 0)
{
if (joinSecond != 0)
{
return;
}
}
else
{
if (joinSecond == 0 || buffer.Count > 3)
{
return;
}
buffer.Add(indexFirst);
buffer.Add(indexSecond);
}
}
if (buffer.Count == 4)
{
var reducded = Fetch(
value,
first.Intersected.FirstOrDefault(r => r.RegionType == otherType),
state,
events);
reducded |= Fetch(
value,
second.Intersected.FirstOrDefault(r => r.RegionType == otherType),
state,
events);
if (reducded)
{
events.Add(ReducedOptions.Ctor <ReduceXWing>());
}
}
}
/// <summary>Initializes all sub square regions.</summary>
private void InitializeSubSquareRegions(int size)
{
for (var xSub = 0; xSub < size; xSub++)
{
for (var ySub = 0; ySub < size; ySub++)
{
var region = new SudokuRegion(SudokuRegionType.Block);
Regions.Add(region);
for (var x = 0; x < size; x++)
{
for (var y = 0; y < size; y++)
{
region.Add(Grid[xSub * size + x, ySub * size + y]);
}
}
}
}
}
/// <summary>Returns true if the other has a intersection with this region of at least 2 cells, but is not the same region.</summary>
public bool HasIntersectionOf2OrMoreSquares(SudokuRegion other)
{
if (other == this)
{
return(false);
}
var count = 0;
foreach (var index in this)
{
if (other.Contains(index))
{
count++;
}
if (count > 1)
{
break;
}
}
return(count > 1);
}
private void Solve(SudokuState state, SudokuRegion region, SudokuRegion intersected, uint value, ICollection <IEvent> events)
{
var count = 0;
foreach (var index in region)
{
if ((state[index] & value) != 0)
{
if (intersection.Contains(index))
{
count++;
}
else
{
return;
}
}
}
if (count > 1)
{
Fetch(value, intersection, intersected, state, events);
}
}
private bool Fetch(uint value, SudokuRegion region, SudokuState state, ICollection <IEvent> events)
{
var reducded = false;
var mask = ~value;
foreach (var index in region)
{
if (buffer.Contains(index))
{
continue;
}
var result = state.And <ReduceXWing>(index, mask);
if (result is ValueFound)
{
events.Add(result);
}
else if (result is ReducedOption)
{
reducded = true;
}
}
return(reducded);
}