/**
* Loads the level collection stored in the passed file.
*
* @param collectionFilePath path and name of the collection to load
* @return the <code>LevelCollection</code> created from the read in data
* @throws IOException the collection file couldn't be read
*/
public final LevelCollection getLevelCollectionFromFile(String collectionFilePath)
throws IOException {
// ArrayList, for storing the read data.
List<String> inputData = new ArrayList<String>(1000);
// Create BufferedReader for the input file.
BufferedReader levelFile = Utilities.getBufferedReader(collectionFilePath);
// The file hasn't been found => return null.
if (levelFile == null) {
throw new FileNotFoundException(Texts.getText("message.fileMissing", collectionFilePath));
}
// Read in line by line of the input data.
String levelDataRow;
try {
while ((levelDataRow = levelFile.readLine()) != null) {
inputData.add(levelDataRow);
}
} finally {
levelFile.close();
}
// Parse the read data and return the collection created from that data.
// The level collection to be returned.
LevelCollection levelCollection = dataParser.extractData(inputData, collectionFilePath);
// Return the collection.
return levelCollection;
}
/**
* Tries to solve the level by generating all possible no-deadlock board positions and returns the
* solution path via a global variable.
*/
protected final void forwardSearch() {
// Hold a box position and the new box position.
int boxPosition;
int newBoxPosition = 0;
// Object for the current board position
IBoardPositionMoves currentBoardPositionWithMoves;
// The board position to be analyzed further.
IBoardPositionMoves boardPositionToBeAnalyzed;
// Object only used for avoiding too many casts.
IBoardPositionMoves oldBoardPositionWithMoves;
// If a board position is reached that has been reached before this object holds
// the board position that has been reached before.
IBoardPosition oldBoardPosition;
// Pushes lower bound of a board position.
int currentBoardPositionLowerBound = 0;
// Number of moves the player has gone for reaching the current board position.
short numberOfMovesSoFar = 0;
// Number of moves and pushes of the current best known solution.
int numberOfMovesBestSolution = Integer.MAX_VALUE;
int numberOfPushesBestSolution = Integer.MAX_VALUE;
// Number of the pushed box.
int pushedBoxNo = 0;
// Number of pushes of the board positions.
int numberOfPushesOldBoardPosition = 0;
int numberOfPushesCurrentBoardPosition = 0;
// Lowest number of moves of a board position in the queue so far.
int shortestSolutionPathLengthSoFar = 0;
// The board position with the lowest estimated solution path length is analyzed further next.
while ((boardPositionToBeAnalyzed = getBestBoardPosition()) != null && isCancelled() == false) {
// Set the board position.
board.setBoardPosition(boardPositionToBeAnalyzed);
// Determine the reachable squares of the player. These squares are used even after
// the deadlock detection, hence they are calculated in an extra object.
playersReachableSquaresMoves.update();
// Get number of the last pushed box.
pushedBoxNo = boardPositionToBeAnalyzed.getBoxNo();
// If no box has been pushed the pushed box number is set to -1, so the tunnel detection isn't
// performed.
if (pushedBoxNo == NO_BOX_PUSHED) {
pushedBoxNo = -1;
}
// Calculate the number of pushes of the new board positions that are created.
numberOfPushesCurrentBoardPosition = boardPositionToBeAnalyzed.getPushesCount() + 1;
// Loop over all boxes. The last pushed box is considered first.
for (int boxCounter = -1, boxNo; boxCounter < board.boxCount; boxCounter++) {
// The last pushed box has already been processed (-> boxCounter = -1)
if (boxCounter == pushedBoxNo) {
continue;
}
// The last pushed box is considered first. It is checked for being in a tunnel.
if (boxCounter == -1) {
boxNo = pushedBoxNo;
// If the box is in a tunnel only pushes of this box have to be considered!
if (isBoxInATunnel(pushedBoxNo, boardPositionToBeAnalyzed.getDirection())) {
boxCounter = board.goalsCount;
}
} else {
boxNo = boxCounter;
}
// Get the position of the box
boxPosition = board.boxData.getBoxPosition(boxNo);
// Push the box to every direction possible.
for (int direction = 0; direction < 4; direction++) {
// Calculate the new box position.
newBoxPosition = boxPosition + offset[direction];
// Immediately continue with the next direction if the player can't reach the correct
// position for pushing or the new box position isn't accessible.
if (playersReachableSquaresMoves.isSquareReachable(boxPosition - offset[direction])
== false
|| board.isAccessibleBox(newBoxPosition) == false) {
continue;
}
// Do push.
board.pushBox(boxPosition, newBoxPosition);
board.playerPosition = boxPosition;
// Calculate the number of moves so far.
numberOfMovesSoFar =
(short)
(boardPositionToBeAnalyzed.getTotalMovesCount()
+ playersReachableSquaresMoves.getDistance(boxPosition - offset[direction])
+ 1);
// Immediately continue with the next direction if the the board position isn't
// reached better than the current best solution.
if (numberOfPushesCurrentBoardPosition > numberOfPushesBestSolution
|| numberOfPushesCurrentBoardPosition == numberOfPushesBestSolution
&& numberOfMovesSoFar >= numberOfMovesBestSolution) {
board.pushBoxUndo(newBoxPosition, boxPosition);
continue;
}
// Create object of the current board position.
currentBoardPositionWithMoves =
new RelativeBoardPositionMoves(board, boxNo, direction, boardPositionToBeAnalyzed);
// Try to read the current board position of the hash table.
oldBoardPosition = positionStorage.getBoardPosition(currentBoardPositionWithMoves);
// If the board position had already been saved in the hash table it must be checked
// for being better than the one in the hash table (it may have already been reached
// by the corral detection hence there has to be a check for a SearchBoardPosition!)
if (oldBoardPosition instanceof IBoardPositionMoves) {
// For avoiding too many casts.
oldBoardPositionWithMoves = (IBoardPositionMoves) oldBoardPosition;
// Calculate the number of pushes of the old board position.
numberOfPushesOldBoardPosition = oldBoardPositionWithMoves.getPushesCount();
// If the current board position has been reached better than the one in the
// hash table it has to be saved / used instead of the old one.
if (numberOfPushesCurrentBoardPosition < numberOfPushesOldBoardPosition
|| numberOfPushesCurrentBoardPosition == numberOfPushesOldBoardPosition
&& numberOfMovesSoFar < oldBoardPositionWithMoves.getTotalMovesCount()) {
// Save the number of moves in the current board position.
currentBoardPositionWithMoves.setMovesCount(numberOfMovesSoFar);
// Replace the old board position by the new one in the hash table.
positionStorage.storeBoardPosition(currentBoardPositionWithMoves);
// The current board position is saved for further analyzing.
storeBoardPosition(currentBoardPositionWithMoves);
}
// Undo push and continue with next direction.
board.pushBoxUndo(newBoxPosition, boxPosition);
continue;
}
/*
* The board position hasn't already been in the hash table, hence it is a new one.
*/
currentBoardPositionLowerBound =
lowerBoundCalcuation.calculatePushesLowerBound(newBoxPosition);
// Undo push (the player is new positioned for the next board position anyway)
board.pushBoxUndo(newBoxPosition, boxPosition);
// Immediately continue with the next direction if the current board position is a
// deadlock
// or the estimated solution path length is higher/equal than the best known solution path
// length.
if (currentBoardPositionLowerBound == LowerBoundCalculation.DEADLOCK
|| numberOfPushesCurrentBoardPosition == numberOfPushesBestSolution
&& numberOfMovesSoFar + currentBoardPositionLowerBound
>= numberOfMovesBestSolution) {
continue;
}
// Save the number of moves in the current board position.
currentBoardPositionWithMoves.setMovesCount(numberOfMovesSoFar);
// If a solution has been found the number of moves and the board position itself
// are saved. This solution is push optimal, but it needn't to be the one with
// best moves, too!
if (currentBoardPositionLowerBound == 0) {
numberOfMovesBestSolution = numberOfMovesSoFar;
numberOfPushesBestSolution = numberOfPushesCurrentBoardPosition;
solutionBoardPosition = currentBoardPositionWithMoves;
if (Debug.isDebugModeActivated) {
System.out.println(
"Solution Found "
+ "Moves/Pushes: "
+ currentBoardPositionWithMoves.getTotalMovesCount()
+ "/"
+ currentBoardPositionWithMoves.getPushesCount());
}
continue;
}
// Calculate the number of no deadlock board positions reached during the search.
boardPositionsCount++;
// Display info about the search (every 5000 board positions and every time the search
// depths has been increased)
if (boardPositionsCount % 5000 == 0
|| shortestSolutionPathLengthSoFar != shortestSolutionPathLength) {
if (shortestSolutionPathLengthSoFar != shortestSolutionPathLength) {
shortestSolutionPathLengthSoFar = shortestSolutionPathLength;
}
publish(
Texts.getText("numberofpositions")
+ boardPositionsCount
+ ", "
+ Texts.getText("searchdepth")
+ shortestSolutionPathLength
+ " "
+ Texts.getText("moves"));
// Throw "out of memory" if less than 15MB RAM is free.
if (Utilities.getMaxUsableRAMinMiB() <= 15) {
isSolverStoppedDueToOutOfMemory = true;
cancel(true);
}
}
// Save the board position in the hash table for further searching.
positionStorage.storeBoardPosition(currentBoardPositionWithMoves);
storeBoardPosition(currentBoardPositionWithMoves);
}
}
}
}
