/**
* The heuristic evaluation function that determines the chances of winning...
*
* @param brd board to be evaluated
* @return score that indicates our chances of winning
*/
protected static int evalBoard(BreakthroughState brd) {
int score = 0;
for (int r = 0; r < BreakthroughState.N; r++) {
for (int c = 0; c < BreakthroughState.N; c++) {
if (brd.board[r][c] == BreakthroughState.homeSym) {
score += (r + 1);
} else if (brd.board[r][c] == BreakthroughState.awaySym) {
score -= (BreakthroughState.N - r);
}
}
}
if (Math.abs(score) > MAX_EVAL_SCORE) {
System.err.println("Problem with eval");
System.exit(0);
}
return score;
}
public void alphabetaTT(char[][] map, int d, double a, double b, boolean isHome, Move[] stack) {
double ev_tem = 0;
ev_tem = ev2(map, isHome);
if (d == MAX_DEPTH || Math.abs(ev_tem) == MAX_SCORE) {
stack[d].score = ev_tem;
return;
}
Board board = new Board(map, isHome, "alphabetatt");
TTEntry tte = tt.getEntry(board.getHashKey());
if (tte != null && tte.getDepth() <= d) {
if (tte.getType() == TTEntry.NT.EXACT) {
stack[d].score = tte.getScore();
return;
}
if (tte.getType() == TTEntry.NT.LOWERBOUND && tte.getScore() > a) a = tte.getScore();
else if (tte.getType() == TTEntry.NT.UPPERBOUNT && tte.getScore() < b) b = tte.getScore();
if (a >= b) {
stack[d].score = tte.getScore();
return;
}
}
if (board.getSize() == 0) System.out.println(isHome + "\t" + d);
Move move;
if (isHome) {
double v = Double.NEGATIVE_INFINITY;
while (board.hasNext()) {
if (FIRST_LAYER_DEBUG == 1 && d == 0)
System.out.println("Home: 0 Total: " + board.getSize());
move = board.next();
map[move.row1][move.col1] = homeSym;
map[move.row2][move.col2] = homeSym;
if (d + 1 == MAX_DEPTH) {
stack[d + 1].set(move.row1, move.col1, move.row2, move.col2);
}
alphabetaTT(map, d + 1, a, b, false, stack);
if (stack[d + 1].score > v) {
v = stack[d + 1].score;
stack[d].set(move.row1, move.col1, move.row2, move.col2, v);
}
map[move.row1][move.col1] = emptySym;
map[move.row2][move.col2] = emptySym;
a = Math.max(a, stack[d].score);
if (stack[d].score >= b || stack[d].score == MAX_SCORE) return;
}
if (stack[d].score < a)
tt.store(new TTEntry(board.getHashKey(), stack[d].score, TTEntry.NT.LOWERBOUND, d));
else if (stack[d].score > b)
tt.store(new TTEntry(board.getHashKey(), stack[d].score, TTEntry.NT.UPPERBOUNT, d));
return;
} else {
double v = Double.POSITIVE_INFINITY;
while (board.hasNext()) {
if (FIRST_LAYER_DEBUG == 1 && d == 0)
System.out.println("Away: 0 Total: " + board.getSize());
move = board.next();
map[move.row1][move.col1] = awaySym;
map[move.row2][move.col2] = awaySym;
if (d + 1 == MAX_DEPTH) {
stack[d + 1].set(move.row1, move.col1, move.row2, move.col2);
}
alphabetaTT(map, d + 1, a, b, true, stack);
if (stack[d + 1].score < v) {
v = stack[d + 1].score;
stack[d].set(move.row1, move.col1, move.row2, move.col2, v);
}
map[move.row1][move.col1] = emptySym;
map[move.row2][move.col2] = emptySym;
b = Math.min(b, stack[d].score);
if (stack[d].score <= a || stack[d].score == -MAX_SCORE) return;
}
if (stack[d].score < a)
tt.store(new TTEntry(board.getHashKey(), stack[d].score, TTEntry.NT.LOWERBOUND, d));
else if (stack[d].score > b)
tt.store(new TTEntry(board.getHashKey(), stack[d].score, TTEntry.NT.UPPERBOUNT, d));
return;
}
}