I have been making a mancala bot using a minimax algorithim. It works for the first bit but it often just gives an output landing on a blank space. Anyone have any idea how to fix this so it plays well?
Here is my code:
function increment(board, ltif, player, re) {
let a = 0;
for(let i = 0; i < board[ltif]; i++) {
if((player && (ltif+i+a+1)%14 == 13) || (!player && (ltif+i+a+1)%14 == 6)) {
a += 1;
}
board[(ltif + i + a + 1)%14] += 1;
}
const bltif = board[ltif];
board[ltif] = 0;
let ans;
board[(bltif + ltif + a)%14] == 1 || (bltif + ltif + a)%14 == 6 || (bltif + ltif + a)%14 == 13 ? ans = board : ans = increment(board, (bltif + ltif + a)%14, player);
if(((bltif + ltif + a)%14 == 6 || (bltif + ltif + a)%14 == 13) && !re) {
ans = 2;;
}
if(board[(bltif + ltif + a)%14] == 1 && !re) {
ans = 3;
}
return ans;
}
function minimax(board, depth, player) {
if(board[6] > 24) {
return 15;
}else if(board[13] > 24) {
return -15;
}else if(board[6] == 24 && board[13] == 24) {
return 0;
}else if(depth === 0) {
return Math.floor((board[6]-board[13])/2);
}
let avail = board.map((element, index) => (element !== 0 && ((index < 6 && player)|| (index < 13 && index > 6 && !player)) ? index : -1)).filter(element => element !== -1);
if(player) {
let maxEval = [-Infinity];
for(let i = 0; i < avail.length; i++) {
let tboard = increment(board.slice(), avail[i], player, false);
let Eval;
if(tboard == 2) {
Eval = 13;
tboard = increment(board.slice(), avail[i], player, true);
}else if(tboard == 3) {
Eval = -13;
tboard = increment(board.slice(), avail[i], player, true);
}else{
Eval = minimax(tboard, depth - 1, false);
}
maxEval = [Math.max(Eval, maxEval[0]),avail[i],tboard];
}
final = [maxEval[1], maxEval[2]];
return maxEval[0];
}else{
let minEval = +Infinity;
for(let i = 0; i < avail.length; i++) {
let tboard = increment(board.slice(), avail[i], player, false);
let Eval;
if(tboard == 2) {
Eval = 13;
tboard = increment(board.slice(), avail[i], player, true);
}else if(tboard == 3) {
Eval = -13;
tboard = increment(board.slice(), avail[i], player, true);
}else{
Eval = minimax(tboard, depth - 1, false);
}
minEval = Math.min(Eval, minEval);
}
return minEval;
}
}
minimax([
5, 0, 5, 5, 5, 0,
3, 5, 5, 0, 5, 5,
5, 0
], 9, true);
console.log(final);
It runs out of a text based editor so thats why the output is into console and it only checks one board then you have to input another. Also just to clarify it is the avalanche version of mancala. I do not have much experience using a minimax algorithm so if anyone has any insight into the problem that would be very helpful. One example of this is that when given the board state [5, 0, 5, 5, 5, 0, 3, 5, 5, 0, 5, 5, 5, 0] it tells me to move the one on the 4th spot of the array so 5 from the right which gives this output: [
5, 0, 5, 5, 0, 1,
4, 6, 6, 1, 5, 5,
5, 0
]. There are much better possible moves and I have no idea why the algorithm is selecting this. Also, the minimax algorithm I am using does not use alpha-beta pruning which is intended and not just a mistake in the code.
