public override bool Equals(object o)
{
if (this == o)
{
return(true);
}
if (o != null && GetType() == o.GetType())
{
NQueensBoard aBoard = (NQueensBoard)o;
if (aBoard.getQueenPositions().Size() != getQueenPositions().Size())
{
return(false);
}
for (int i = 0; i < getSize(); ++i)
{
for (int j = 0; j < getSize(); j++)
{
if (queenExistsAt(i, j) != aBoard.queenExistsAt(i, j))
{
return(false);
}
}
}
return(true);
}
return(false);
}
public static NQueensBoard getBoardForIndividual(Individual <int> individual)
{
int boardSize = individual.length();
NQueensBoard board = new NQueensBoard(boardSize);
for (int i = 0; i < boardSize; ++i)
{
int pos = individual.getRepresentation().Get(i);
board.addQueenAt(new XYLocation(i, pos));
}
return(board);
}
public double apply(Individual <int> individual)
{
double fitness = 0;
NQueensBoard board = getBoardForIndividual(individual);
int boardSize = board.getSize();
// Calculate the number of non-attacking pairs of queens (refer to
// AIMA
// page 117).
ICollection <XYLocation> qPositions = board.getQueenPositions();
for (int fromX = 0; fromX < (boardSize - 1); fromX++)
{
for (int toX = fromX + 1; toX < boardSize; toX++)
{
int fromY = qPositions.Get(fromX).GetYCoOrdinate();
bool nonAttackingPair = true;
// Check right beside
int toY = fromY;
if (board.queenExistsAt(new XYLocation(toX, toY)))
{
nonAttackingPair = false;
}
// Check right and above
toY = fromY - (toX - fromX);
if (toY >= 0)
{
if (board.queenExistsAt(new XYLocation(toX, toY)))
{
nonAttackingPair = false;
}
}
// Check right and below
toY = fromY + (toX - fromX);
if (toY < boardSize)
{
if (board.queenExistsAt(new XYLocation(toX, toY)))
{
nonAttackingPair = false;
}
}
if (nonAttackingPair)
{
fitness += 1.0;
}
}
}
return(fitness);
}
/**
* Implements a GOAL-TEST for the n-queens problem.
*/
public static bool testGoal(NQueensBoard state)
{
return(state.getNumberOfQueensOnBoard() == state.getSize() && state.getNumberOfAttackingPairs() == 0);
}
