// Adds the position and it's estimated utility to the table.
// If the position is already in the table (which will happen sometimes), It will either update.
public void addPositionToListOfAnalysedPositions(
int key[], boolean isDarkPlayerCurrentTurn, int curdepth, double utility) {
boolean alreadyDidPos = false;
AnalysedPosition alreadyAnalysedPos = null;
// check if the position has been inserted after doing the recursion:
if (viewedPos != null) {
alreadyAnalysedPos = viewedPos.search(key);
if (alreadyAnalysedPos != null) {
alreadyDidPos = true;
}
}
// If the position is not already done:
if (alreadyDidPos == false) {
AnalysedPosition pos = new AnalysedPosition(curdepth, isDarkPlayerCurrentTurn, utility, key);
viewedPos = BalancedSearchTree.addValueToTree(viewedPos, pos);
// FOR TEST PURPOSES
numPosRecorded++;
// TESTING SLOW
if (debug) {
sanityCheckNumNodes();
viewedPos.sanityCheckSorted();
}
// END TESTING
// if we only need to update:
} else {
alreadyAnalysedPos.updatePositionWithImprovedCalculation(curdepth, utility);
}
}
public Double getUtilityIfAlreadyFound(int key[], int curdepth) {
if (viewedPos != null) {
AnalysedPosition alreadyAnalysedPos = viewedPos.search(key);
if (alreadyAnalysedPos != null && alreadyAnalysedPos.getDepth() >= curdepth) {
return new Double(alreadyAnalysedPos.getUtility());
}
}
return null;
}
// testing: MAKE SURE THAT THE KEY STAYS THE SAME!!!
public void sanityTestKeyBeforeAndAfter(
CheckersSetup setup, boolean isDarkPlayerCurrentTurn, int key[]) {
int key2[] = AnalysedPosition.makeKey(setup, isDarkPlayerCurrentTurn);
int compare = BalancedSearchTree.compare(key, key2);
if (compare != 0) {
System.out.println("ERROR: the board changes through the getEstUtilityOfPosition function.");
System.exit(1);
}
}
// testing: make sure that the position didn't suddenly get on the list.
public void sanityTestPositionDidntDissapearOffTree(
AnalysedPosition alreadyAnalysedPos, int key[], boolean alreadyDidPos, int curdepth) {
// note: this should not happen within this function.
if (viewedPos != null) {
alreadyAnalysedPos = viewedPos.search(key);
if (alreadyAnalysedPos != null && alreadyDidPos == false) {
if (alreadyAnalysedPos.getDepth() >= curdepth) {
System.out.println("ERROR: Position should have been viewable earlier");
System.exit(1);
}
}
}
}
// pre: this position MUST be at the beginning of a turn.
// post: returns the utility of the checkers position for whoever's turn it happens to be.
public double getEstUtilityOfPosition(
CheckersSetup setup, boolean isDarkPlayerCurrentTurn, int curdepth) {
double ret;
// this key identifies the setup of the board and who's turn it is in 3 numbers:
int key[] = AnalysedPosition.makeKey(setup, isDarkPlayerCurrentTurn);
// ret pos!!!!
// Check to see if the position has already been analysed
Double alreadyFoundUtility = getUtilityIfAlreadyFound(key, curdepth);
if (alreadyFoundUtility != null) {
return new Double(alreadyFoundUtility).doubleValue();
}
// end check
// Find the utility from scratch and recursion:
if (curdepth == 0) {
if (isDarkPlayerCurrentTurn) {
return utilityFunc.getEstimatedUtilityForDarkPlayer(setup, isDarkPlayerCurrentTurn);
} else {
return -utilityFunc.getEstimatedUtilityForDarkPlayer(setup, isDarkPlayerCurrentTurn);
}
} else {
ArrayList<checkersSetup.Turn> turnChoices =
BasicCheckersAIFunctions.getAllPossiblePlayerOptionsFor1Turn(
setup, isDarkPlayerCurrentTurn);
if (turnChoices.size() == 0) {
// horrible position:
return -BasicCheckersAIFunctions.DARK_WIN_UTILITY;
}
setup.playTurn(turnChoices.get(0));
// op = OPPONENT!
double opWorstPosUtil =
getEstUtilityOfPosition(setup, !isDarkPlayerCurrentTurn, curdepth - 1);
setup.reverseTurn(turnChoices.get(0));
double currOpPosUtil;
for (int i = 1; i < turnChoices.size(); i++) {
setup.playTurn(turnChoices.get(i));
currOpPosUtil = getEstUtilityOfPosition(setup, !isDarkPlayerCurrentTurn, curdepth - 1);
if (currOpPosUtil < opWorstPosUtil) {
opWorstPosUtil = currOpPosUtil;
}
setup.reverseTurn(turnChoices.get(i));
}
ret = -opWorstPosUtil;
// End finding utility from scratch
// TESTING SLOW
if (debug) {
sanityTestKeyBeforeAndAfter(setup, isDarkPlayerCurrentTurn, key);
}
// END TESTING
// ADD analysed position to tree:
addPositionToListOfAnalysedPositions(key, isDarkPlayerCurrentTurn, curdepth, ret);
return ret;
}
}
