// Returns true if placing a stone with color color on point coord is legal
private bool LegalMove(Coord coord, State color, State opponent)
{
HashSet <Coord> neighbours = GetNeighbours(coord);
if (_gridStones[coord.Column, coord.Row] != State.None) // there is a stone placed
{
return(false);
}
if (GetColoredNeighbour(neighbours, State.None).Count != 0)
{
return(true);
}
foreach (Coord n in GetColoredNeighbour(neighbours, color))
{
AbGroup g = _groups[_gridGroups[n.Column, n.Row]];
// If the stone connects to a stone with 2 or more liberties It will not be captured.
if (g.GetLiberties().Count > 1)
{
return(true);
}
}
foreach (Coord n in GetColoredNeighbour(neighbours, opponent))
{
AbGroup g = _groups[_gridGroups[n.Column, n.Row]];
// If any opponent group has one liberty that group is captured and the move is Legal, as it now has a liberty.
if (g.GetLiberties().Count == 1)
{
return(true);
}
}
return(false);
}
// Remove all groups that are marked dead
public override void DeleteDead()
{
foreach (int groupId in _markedGroups)
{
AbGroup groupToDelete = _groups[groupId];
State opponentColor = groupToDelete.GetColor();
switch (opponentColor)
{
case State.Black:
Capture(groupToDelete, State.White);
break;
case State.White:
Capture(groupToDelete, State.Black);
break;
case State.None:
break;
default:
throw new ArgumentOutOfRangeException();
}
}
_markedGroups.RemoveWhere(c => _markedGroups.Contains(c));
}
/**
* This method will remove a captured group
* Each stone in the group is removed from the board and added as a liberty for all other groups
*/
private void Capture(AbGroup capturedGroup, State color)
{
foreach (Coord coord in capturedGroup.GetStones())
{
// Update the board and add the capture
_gridStones[coord.Column, coord.Row] = State.None;
_gridGroups[coord.Column, coord.Row] = 0;
switch (color)
{
case State.Black:
_capBlack++;
break;
case State.White:
_capWhite++;
break;
case State.None:
break;
default:
throw new ArgumentOutOfRangeException(nameof(color), color, null);
}
// Update all groups liberties/adjacent data
foreach (Group g in _groups.Values)
{
g.RemoveStone(coord);
}
}
// Remove the group from the board
DeleteGroup(capturedGroup);
}
public override void MergeGroup(AbGroup slaveGroup)
{
_stones.UnionWith(slaveGroup.GetStones());
_liberties.UnionWith(slaveGroup.GetLiberties());
_adjacent.UnionWith(slaveGroup.GetAdjacent());
foreach (Coord coord in _stones)
{
_liberties.RemoveWhere(c => c.Row == coord.Row && c.Column == coord.Column);
}
}
// This method updates the group grid, consuming all stones in the SlaveGroup to the MAsterGroup
private void MergeGroupGrid(AbGroup masterGroup, AbGroup slaveGroup)
{
for (var i = 0; i < _size; i++)
{
for (var j = 0; j < _size; j++)
{
if (_gridGroups[i, j] == slaveGroup.GetId())
{
_gridGroups[i, j] = masterGroup.GetId();
}
}
}
}
/**
* This method Updates the state of the board with the addition of the new stone
*/
private void UpdateBoard(Coord coord, State color, State opponent)
{
_gridStones[coord.Column, coord.Row] = color; //Place the stone
HashSet <Coord> neigh = GetNeighbours(coord); // Get the neighboouring coords.
var g = new Group(GetNextGroupId(), coord, color, GetColoredNeighbour(neigh, State.None),
GetColoredNeighbour(neigh, opponent)); //Create the group
_groups.Add(g.GetId(), g); // Add the group to the board
_gridGroups[coord.Column, coord.Row] = g.GetId(); //Add group to grid
foreach (Coord pos in neigh) //Merge adjacent groups of same color into this group.
{
int groupId = _gridGroups[pos.Column, pos.Row];
if (!_groups.ContainsKey(groupId) || groupId == g.GetId()) // If there is no group of the ID do nothing
{
continue;
}
AbGroup ng = _groups[_gridGroups[pos.Column, pos.Row]];
if (ng?.GetColor() == color) // If the group is of the same collor merge the groups
{
MergeGroupGrid(g, ng);
MergeGroup(g, ng);
g.AddStone(coord);
}
else if (ng?.GetColor() == opponent) // If the gorup is of the opponent
{
ng.AddStone(coord);
if (ng.GetLiberties().Count == 0) // If we removed the last liberty capture the group
{
Capture(ng, color);
}
}
}
// These methods prints the board and some debugg information in the output.
WriteGroupBoard();
WriteGroupLiberties();
}
// Consumes the argument group into this group public abstract void MergeGroup(AbGroup group);
// Removes the group from the Board
private void DeleteGroup(AbGroup group)
{
_groups.Remove(group.GetId());
}
/**
* This method merges group1 with group2
* All stones and liberties from group2 will be added to group1
* Group 2 will be deleted.
*/
private void MergeGroup(AbGroup group1, AbGroup group2)
{
group1.MergeGroup(group2);
DeleteGroup(group2);
}