// TODO: again, NPuzzleState return type instead of int[]
public override NPuzzleState <int[]> Result(NPuzzleState <int[]> s, int action)
{
int[] state = s.State;
int[] newState = new int[state.Length];
int emptyIndex;
state.CopyTo(newState, 0);
emptyIndex = GetEmptyIndex(state);
if (emptyIndex == -1)
{
NPuzzleUtils.MissingEmptyElementException ex = new NPuzzleUtils.MissingEmptyElementException(state.Length.ToString());
throw ex;
}
if (AcceptableAction(state, emptyIndex, action))
{
if (action == 1)
{
NPuzzleUtils.Swap(newState, emptyIndex, emptyIndex + 1);
}
else if (action == -1)
{
NPuzzleUtils.Swap(newState, emptyIndex, emptyIndex - 1);
}
else if (action == -2)
{
NPuzzleUtils.Swap(newState, emptyIndex, emptyIndex + dimension);
}
else
{
NPuzzleUtils.Swap(newState, emptyIndex, emptyIndex - dimension);
}
}
else
{
String msg = String.Format("You entered an invalid action: {0} for the state {1}", action, state.ToString());
NPuzzleUtils.ResultAcceptableActionException ex = new NPuzzleUtils.ResultAcceptableActionException(msg);
throw ex;
}
return(new NPuzzleState <int[]>(newState));
}
/*!
* Get all the actions possible in a givens state.
* First, we must locate the index of the 'empty'
* space in the 'board' (array), which in this case
* is equal to 'size'.
*
* We can determine the possible actions by the direction the
* 'empty' space can be moved: up, down, left or right
* We'll use the following conventions:
*
* up : 2
* down: -2
* left: -1
* right: 1
*
*
*/
// TODO: use State instead of int[]
public override List <int> Actions(NPuzzleState <int[]> s)
{
int[] state = s.State;
int emptyIndex = GetEmptyIndex(state);
if (emptyIndex == -1)
{
NPuzzleUtils.MissingEmptyElementException ex = new NPuzzleUtils.MissingEmptyElementException(state.Length.ToString());
throw ex;
}
List <int> actions = new List <int>();
//! if emptyIndex is in the rightmost column,
//! then adding one to it will be divisible by dimension
if ((emptyIndex + 1) % dimension != 0)
{
actions.Add(1);
}
//! if emptyIndex is in the leftmost column,
//! it can be divided by dimension
//! Anything not in the leftmost column can be moved left, or - 1
if (emptyIndex % dimension != 0)
{
actions.Add(-1);
}
//! if emptyIndex is greater than or equal to dim, it
//! must not be in the first row, and hence
//! can be moved up, or 2
if (emptyIndex >= dimension)
{
actions.Add(2);
}
if (emptyIndex < size - dimension)
{
actions.Add(-2);
}
return(actions);
}