我正在努力进行极小极大运动，我只是试图用它连接四个ai。当我只深入探索一个节点时，我的工作正常，但我无法弄清楚为什么它一旦深入就会混乱。
private int minimax(Gameboard gameBoard, int alpha, int depth, char color) {
Gameboard gb = new Gameboard(gameBoard);
int value = 0;
int bestChoice = 0;
int bestValue = alpha;
// determine which use the value is for
if (gb.computerColor == color) {
value = 1;
} else {
value = -1;
}
if (gb.CheckForWinner(gb.lastSpacePlayed)) {
if(gb.winner == gb.computerColor){
bestValue = (1000000000 - depth);
}else{
bestValue = (-1000000000 - depth);
}
}
// get the bestValue at our maximum recrusion depth
else if (depth == maxDepth) {
int moveWeight = (threatLevel(gb, color));
if (moveWeight != 0) {
bestValue = value * (moveWeight - depth);
} else {
bestValue = moveWeight;
}
} else {
// Generate moves for each col and find the best score from each of
// the generated moves.
for (int c = 0; c < 7; c++) {
Gameboard game = new Gameboard(gb);
int selectedPlace = game.PlacePiece(c, color);
// Recursive call the generated game grid and compare the
// current value to move value
// If move is higher, make it the new current value.
if (selectedPlace != -1) {
char tempColor;
// change the user for the child node after a piece is played
if (color == 'Y') {
tempColor = 'R';
} else {
tempColor = 'Y';
}
// call the function so we can explore to maximum depth
if (depth < maxDepth) {
int v = minimax(new Gameboard(game), -1000000, depth + 1, tempColor);
if (v > bestValue) {
bestChoice = c;
bestValue = v;
}
System.out.println(v);
}
}
}
}
if (depth == 0) {
if (threatLevel(gb, gb.lastSpacePlayed.getColor()) == 0) {
return gb.spaces.get(0).get(3).getColor() == gb.playerColor ? 2
: 3;
} else {
return bestChoice;
}
} else {
return bestValue;
}
}
我是以return minimax(gameBoard, -1000000, 0, gameBoard.computerColor);
我的理解是循环遍历所有子节点，如果节点与父节点相同则返回值为最大值，如果节点不相同则返回最小值。任何方向将不胜感激。
答案 0 :(得分：1)
private int minimax(Gameboard gameBoard, int depth, char color) {
Gameboard gb = new Gameboard(gameBoard);
int bestChoice = 0;
int bestValue = 0;
//If we've won, return highest possible value. If we've lost, return lowest.
if (gb.CheckForWinner(gb.lastSpacePlayed)) {
if(gb.winner == color){
return Integer.MAX_VALUE
}else{
return Integer.MIN_VALUE
}
}
//if we hit maximum depth, resort to our heuristic method.
else if (depth == maxDepth) {
return threatLevel(gb, color);
} else {
// Generate moves for each col and find the best score from each of
// the generated moves. Keep track of the worst one.
int worstBestResponse = Integer.MAX_INT
boolean tie = true;
for (int c = 0; c < 7; c++) {
Gameboard game = new Gameboard(gb);
int selectedPlace = game.PlacePiece(c, color);
// Recursive call the generated game grid and compare the
// current value to move value
// If move is higher, make it the new current value.
if (selectedPlace != -1) {
tie = false;
char tempColor;
// change the user for the child node after a piece is played
if (color == 'Y') {
tempColor = 'R';
} else {
tempColor = 'Y';
}
// call the function so we can explore to maximum depth
if (depth < maxDepth) {
int v = minimax(new Gameboard(game), depth + 1, tempColor);
if (v < worstBestResponse) {
worstBestResponse = v;
}
}
}
}
if(tie) {
//if game is a tie, we return 0, to show no favour.
return 0;
} else {
//After determining the value of the opponents best response, we return the negative value of it. That is, what's bad for them is good for us and visa versa.
return -worstBestResponse;
}
}
}
我相信这样的事情更像是你正在寻找的东西。这假设威胁等级是一种启发式方法，用于确定在给定游戏中大约谁赢了。
我已经掌握了该方法可能具有的关于它的根源的任何知识。它应该只适用于任何人和＃34;颜色＆＃34;是。我还清理了你的任意大整数以显示输赢。 MAX_VALUE和MIN_VALUE更加优雅。
无论如何，尝试一下，并以深度为0调用它。如果您有疑问，请告诉我
答案 1 :(得分：0)
如果您的方法不起作用，您可以尝试模仿wiki或here上的伪代码的基本结构。在java中我有：
/**
* initialize MiniMax(0, player1) where player1 is computer
* @param deg depth
* @param player either MAX or MIN
* @return int {score,column}
*/
int[] MiniMax(int deg, char player) {
// list of possible columns to place a checker
List<int[]> moves = nextMoves();
int v;
char prev;
if (player==player1) prev = player2;
else prev = player1;
// IF depth = 0 OR there is a connect 4 OR the board is full (draw) THEN
// return your static evaluation (heuristic)
// if the current position has a connect 4, return -inf or inf
// depending on if player is MIN or MAX respectively
if (checkPos(prev) || (deg == this.deg) || moves.isEmpty())
return new int[] {eval(),bestMove};
//MAX
else if (player==player1) {
v = -inf;
for (int[] move : moves) { // move = {row,column}
board[move[0]][move[1]] = player1; // make move
int score = MiniMax(deg+1,player2)[0];
board[move[0]][move[1]] = ' '; // undo move
if (score>v) {
v = score;
bestMove = move[1];
}
}
return new int[] {v,bestMove};
}
//MIN
else {
v = inf;
for (int[] move : moves) { // move = {row,column}
board[move[0]][move[1]] = player2; // make move
int score = MiniMax(deg+1,player1)[0];
board[move[0]][move[1]] = ' '; // undo move
if (v>score) {
v = score;
bestMove = move[1];
}
}
return new int[] {v,bestMove};
}
}
使用字符数组或其他东西而不是class来表示电路板可能很有用。最有效的方法是将电路板表示为long，因为您可以检查是否存在使用4位移位的连接四。这是一些草率的Java，显示上面的东西工作：
import java.util.ArrayList;
import java.util.List;
public class Connect4 {
static final int WIDTH = 7;
static final int HEIGHT = 6;
private static final int inf = 9999999;
private static final char player1 = 'X';
private static final char player2 = 'O';
char[][] board = new char[WIDTH][HEIGHT];
private int deg;
int bestMove;
static char[][] copy(char[][] aArray) {
char[][] copy = new char[aArray.length][aArray[0].length];
for (int idy = 0; idy < aArray.length; ++idy) {
for (int idx = 0; idx < aArray[0].length; ++idx) {
copy[idy][idx] = aArray[idy][idx];
}
}
return copy;
}
void prints() {
System.out.println();
for (int i = 0; i < 6; i++) {
System.out.println("=============================");
for (int j = 0; j < 7; j++) {
if (j == (WIDTH - 1)) {
if (board[i][j]==' ') {
System.out.println("| |");
}
else {
if(board[i][j]==player1 ) System.out.println("| " +"\u001B[32m"+board[i][j]+"\u001B[0m" + " |");
else System.out.println("| " +"\u001B[34m"+board[i][j]+"\u001B[0m" + " |");
}
}
else {
if (board[i][j]==' ') {
System.out.print("| ");
}
else {
if(board[i][j]==player1 ) System.out.print("| " +"\u001B[32m"+board[i][j]+"\u001B[0m" + " ");
else System.out.print("| " +"\u001B[34m"+board[i][j]+"\u001B[0m" + " ");
}
}
}
}
System.out.println("=============================");
}
//STATIC EVALUATION
int eval3(char player) {
if (checkPos(player)) {
return inf;
}
int count;
int open;
int evaluation = 0;
//evaluation = number of open 3 in rows
//go through all possible 4in rows and check
//horz
for (int i = 0; i < HEIGHT; i++) {
for (int j = 0; j < 4; j++) {
count = 0;
open = 0;
if (board[i][j]==player) count++;
else if(board[i][j]==' ') open++;
if (board[i][j + 1]==player) count++;
else if(board[i][j + 1]==' ') open++;
if (board[i][j + 2]==player) count++;
else if(board[i][j + 2]==' ') open++;
if (board[i][j + 3]==player) count++;
else if(board[i][j + 3]==' ') open++;
if ((count == 3) && (open == 1)) evaluation++;
}
}
//vert
for (int j = 0; j < WIDTH; j++) {
for (int i = 0; i < 3; i++) {
count = 0;
open = 0;
if (board[i][j]==player) count++;
else if (board[i][j]==' ') open++;
if (board[i + 1][j]==player) count++;
else if (board[i+1][j]==' ') open++;
if (board[i + 2][j]==player) count++;
else if (board[i + 2][j]==' ') open++;
if (board[i + 3][j]==player) count++;
else if (board[i + 3][j]==' ') open++;
if ((count == 3) && (open == 1)) evaluation++;
}
}
// pos slope diag
for (int j = 0; j < 4; j++) {
for (int i = 3; i < HEIGHT; i++) {
count = 0;
open = 0;
if (board[i][j]==player) count++;
else if (board[i][j]==' ') open++;
if (board[i - 1][j + 1]==player) count++;
else if (board[i - 1][j + 1]==' ') open++;
if (board[i - 2][j + 2]==player) count++;
else if (board[i - 2][j + 2]==' ') open++;
if (board[i - 3][j + 3]==player) count++;
else if (board[i - 3][j + 3]==' ') open++;
if ((count == 3) && (open == 1)) evaluation++;
}
}
// neg slope diag
for (int j = 0; j < 4; j++) {
for (int i = 0; i < (3); i++) {
count = 0;
open = 0;
if (board[i][j]==player) count++;
else if (board[i][j]==' ') open++;
if (board[i + 1][j + 1]==player) count++;
else if (board[i + 1][j + 1]==' ') open++;
if (board[i + 2][j + 2]==player) count++;
else if (board[i + 2][j + 2]==' ') open++;
if (board[i + 3][j + 3]==player) count++;
else if (board[i + 3][j + 3]==' ') open++;
if ((count == 3) && (open == 1)) evaluation++;
}
}
return evaluation;
}
int eval() {return eval3(player1) - eval3(player2);}
boolean checkPos(char cur) {
//horz
for (int i = 0; i < HEIGHT; i++) {
for (int j = 0; j < 4; j++) {
if ( board[i][j]==cur &&
board[i][j + 1]==cur &&
board[i][j + 2]==cur &&
board[i][j + 3]==cur) {
return true;
}
}
}
//vert
for (int j = 0; j < WIDTH; j++) {
for (int i = 0; i < 3; i++) {
if ( board[i][j]==cur &&
board[i + 1][j]==cur &&
board[i + 2][j]==cur &&
board[i + 3][j]==cur) {
return true;
}
}
}
// pos slope diag
for (int j = 0; j < 4; j++) {
for (int i = 3; i < HEIGHT; i++) {
if ( board[i][j]==cur &&
board[i - 1][j + 1]==cur &&
board[i - 2][j + 2]==cur &&
board[i - 3][j + 3]==cur) {
return true;
}
}
}
// neg slope diag
for (int j = 0; j < 4; j++) {
for (int i = 0; i < 3; i++) {
if ( board[i][j]==cur &&
board[i + 1][j + 1]==cur &&
board[i + 2][j + 2]==cur &&
board[i + 3][j + 3]==cur) {
return true;
}
}
}
return false;
}
List<int[]> nextMoves() {
List<int[]> result = new ArrayList<>();
for (int j = 0; j < WIDTH; j++) {
//if column j isnt full then add
if (board[0][j]==' ') result.add(new int[] {findY(j),j});
}
return result;
}
int findY(int col) {
int i = board.length - 1;
while (i > -1) {
if (board[i][col]==' ') break;
i--;
}
return i;
}
/**
* @param deg depth
* @param player either MAX or MIN
* @return int {score,column}
*/
int[] MiniMax(int deg, char player) {
// list of possible columns to place a checker
List<int[]> moves = nextMoves();
int v;
char prev;
if (player==player1) prev = player2;
else prev = player1;
// IF depth = 0 OR there is a connect 4 OR the board is full (draw) THEN
// return your static evaluation (heuristic)
// if the current position has a connect 4, return -inf or inf
// depending on if player is MIN or MAX respectively
if (checkPos(prev) || (deg == this.deg) || moves.isEmpty())
return new int[] {eval(),bestMove};
//MAX
else if (player==player1) {
v = -inf;
for (int[] move : moves) { // move = {row,column}
board[move[0]][move[1]] = player1; // make move
int score = MiniMax(deg+1,player2)[0];
board[move[0]][move[1]] = ' '; // undo move
if (score>v) {
v = score;
bestMove = move[1];
}
}
return new int[] {v,bestMove};
}
//MIN
else {
v = inf;
for (int[] move : moves) { // move = {row,column}
board[move[0]][move[1]] = player2; // make move
int score = MiniMax(deg+1,player1)[0];
board[move[0]][move[1]] = ' '; // undo move
if (v>score) {
v = score;
bestMove = move[1];
}
}
return new int[] {v,bestMove};
}
}
public static void main(String[] args) {
Connect4 c = new Connect4();
c.deg = 5;
char[][] b = {
{' ',' ',' ',' ',' ',' ',' '},
{' ',' ',' ',' ',' ',' ',' '},
{' ',' ',' ',' ',' ',' ',' '},
{' ',' ',' ',' ',' ',' ',' '},
{' ','X','X','X',' ',' ',' '},
{' ','O','X','X','X',' ',' '}
};
c.board = copy(b);
c.prints();
System.out.println("best value = " + c.MiniMax(0, player1)[1]);
}
}