问题描述
我遇到了一个问题，即 AI 播放器总是播放它遇到的第一个可用移动。我试图让 AI 使用 Minimax 算法。你觉得我能怎么解决？
这是代码（带解释）：
在展示代码之前的一点见解：
- 我试图以这样一种方式设置它，即 AI 播放器（无论它是什么颜色）是最大化播放器。因此，如果玩家回合是白色，但白色是 AI 玩家，则 isMaximizing = true。
- 我想指出这一点，这样玩家在颜色方面的转向和玩家在最大化方面的转向就不会混淆。
我最初使用它的地方：
// AI Hard - Return Minimax
function minimaxAI(){
// Here's where the minimax function is initially called
const AI = (ourPlayer === "white") ? "black" : "white"
const squares = history[history.length - 1].slice()
// AI is the maximizing player so we get -Infinity,it'll try to increase the value of bestscore
let bestscore = -Infinity
let bestMove = null
// Perform minimax algorithm for each valid move and pick the best score
// Get the valid moves for the AI player
const AIValidMoves = checkSquaresForSides()[(AI === "black") ? 0 : 1 ]
for (var aimove=0;aimove<AIValidMoves.length;aimove++){
// Play the AI moves and generate the new board
const crds = AIValidMoves[aimove].turned
crds.unshift(AIValidMoves[aimove].coordinates)
const newBoard = handleMove(crds,squares,AI,false,false)
// Check minimax for the new board
const score = minimax(newBoard,4,false)
// If score is higher than the current one,replace the highest score and the according coordinates
if (score > bestscore || aimove === 0) {
bestscore = score
bestMove = crds
}
}
console.log('Final Value:')
console.log(bestscore)
// Play the move(this time on the real board)
const upcomingAI = handleMove(bestMove)
// Set it as the latest of the collection of squares
setHistory(upcomingAI)
// Useless to kNow for this issue
setStepNumber(upcomingAI.length - 1)
}
Minimax 算法本身：
function minimax(board,depth,isMaximizing) {
const AI = (ourPlayer === "white") ? "black" : "white"
const stones = setStoneCount(board)
// If there's a winner,return Infinity,0 or -Infinity depending on whether AI won,it is a tie or our player won
if (stones[0] === 0 || stones[1] === 0 || stones[0] + stones[1] === 64) {
// Return the score of the move if the game is over
let score = (stones[(AI === "black") ? 1 : 0] === 0) ? Infinity : (stones[stones[0] === stones[1]]) ? 0 : -Infinity
return score
} else if (depth === 0) {
// If the maximal depth is reached,then evaluate the current board by counting all the stones for the both sides and subtracting one from the other appropriately
const squares = setStoneCount(board)
let score = 0
if (AI === "black") {
score = squares[0] - squares[1]
} else if (AI === "white") {
score = squares[1] - squares[0]
}
return score
}
if (isMaximizing) {
// Perform minimax if depth !== 0 and isMaximizing,just like we did initially
let bestscore = -Infinity
// Get the valid moves for the maximizing player
const AIValidMoves = checkSquaresForSides()[(AI === "black") ? 0 : 1 ] // AI Moves because isMaximizing = true
for (var aimove=0;aimove<AIValidMoves.length;aimove++){
const crds = AIValidMoves[aimove].turned
crds.unshift(AIValidMoves[aimove].coordinates)
const newBoard = handleMove(crds,board,false)
// check for isMaximizing
let maximizingNext = !isMaximizing
// If there's no move to make for the one side,player turn might stay the same. Here,I check for those situations
const available = checkSquaresForSides(newBoard)
if (available[0].length === 0) {
if (AI === "white") {
maximizingNext = true
} else {
maximizingNext = false
}
} else if (available[1].length === 0){
if (AI === "black") {
maximizingNext = true
} else {
maximizingNext = false
}
}
// Perform minimax for the new board(depth is one less)
const score = minimax(newBoard,depth - 1,maximizingNext)
// If current score is higher than the highest one caught yet,it should be replaced
if (score > bestscore) {
bestscore = score
}
}
return bestscore
} else {
// Perform minimax if depth !== 0 and isMaximizing
let bestscore = Infinity
// Get the valid squares for the minimizing player
const PlayerValidMoves = checkSquaresForSides()[(AI === "black") ? 1 : 0 ] // Player Moves because isMaximizing = false
// Play each move one-by-one for the minimizing player
for (var playerMove=0;playerMove<PlayerValidMoves.length;playerMove++) {
const crds = PlayerValidMoves[playerMove].turned
crds.unshift(PlayerValidMoves[playerMove].coordinates)
const newBoard = handleMove(crds,ourPlayer,false)
// check for isMaximizing
let maximizingNext = !isMaximizing
// Just like the prevIoUs one,check whether there's an exceptional situation to be considered with the player turn
const available = checkSquaresForSides(newBoard)
if (available[0].length === 0) {
if (AI === "white") {
maximizingNext = true
} else {
maximizingNext = false
}
} else if (available[1].length === 0){
if (AI === "black") {
maximizingNext = true
} else {
maximizingNext = false
}
}
// Perform minimax for the new board
const score = minimax(newBoard,maximizingNext)
// If the current score is lower than the lowest one obtained so far,it should be replaced
if (score < bestscore) {
bestscore = score
}
}
return bestscore
}
}
它最初确实有效，但是当我对达到深度时评估板的方式不满意时。我改了，现在不行了。我不想回到上一个，因为它不准确。但是，为什么 AI 玩家在遇到第一个动作时却没有正确评估？
解决方法
我解决了，只是把板子评估部分改成了这样：
// The initial score
let score = 0
// value board for each square
const sq_val = [
[160,-20,20,5,160],[-20,-40,-5,-20],[20,15,3,20],[5,5],[160,160]
]
// Our stones' positions are looked for and the according values are added or substracted depending on whether the player found is the maximizing player or the minimizing player(AI Player: Maximizing,Our Player: Minimizing)
for (var row=0;row<8;row++)
for (var col=0;col<8;col++) {
if (board[row][col] === AI) {
score += sq_val[row][col]
} else if (board[row][col] === ourPlayer) {
score -= sq_val[row][col]
}
}
}
// The score is returned
return score
顺便说一下，算法现在已经设置好了，但它不是那么准确，因为我需要增加它的深度；为了做到这一点，我必须首先实施 alpha-beta 修剪，这样我们的计算机就不会过热。同时使函数异步在性能方面会更好。