我想扩展我制作的较旧的Tic Tac Toe游戏，使两个玩家可以互相对抗。我想让用户可以选择对付困难的AI。问题是AI不会一直选择最佳动作。例如，如果先走，它将始终选择点1。如果用户选择了点2，它将选择点4。此后，无论用户选择什么（除点7之外），AI都不会选择点7。AI的胜利并非不可避免（用户仍然可以获胜）游戏），所以这不是问题。
感谢您的帮助。谢谢！
我很肯定问题出在我的minimax或bestmove函数上。可能只是我没有通过minimax函数正确实现，但我无法发现问题。
#include <iostream>
#include <iomanip>
#include <string>
#include <array>
// This is a program to play a single game of tic-tac-toe
// between either two human (non-AI) players or an AI.
using namespace std;
void PrintBoard(array <char, 9>);
int programprogress();
int checkwin(array <char, 9>);
int minimax(array <char, 9>, int, int, bool);
int bestMove(array <char, 9>, int);
int Opposite(int);
char PlayerSymbol(int);
const int SIZE = 9;
array <char, SIZE> Pos = { '1', '2', '3', '4', '5', '6', '7', '8', '9' };
int player_number = 1;
int k = -11, result;
bool AI = false, first;
// Global variables used by 2 or more functions.
// Array had to be initialized with numbers instead of blank spaces
// because the check win function wouldn't work properly.
int main()
{
string userinp;
cout << "This is tic tac toe! Here's your board!" << endl;
PrintBoard(Pos);
cout << "Would you like to play versus an AI? (Y/N)" << endl;
cin >> userinp;
if (userinp[0] == 'Y')
{
cout << "Excellent! Would you like to start first, or second? (F/S)" << endl;
cin >> userinp;
if (userinp[0] == 'F')
{
cout << "You will start first!" << endl;
first = false;
player_number = 2;
}
else
{
cout << "The AI will start first!" << endl;
first = true;
}
AI = true;
}
else
{
cout << "Excellent! Your game will start soon." << endl;
}
result = programprogress();
player_number--;
PrintBoard(Pos);
if (result == 1)
cout << endl << "Player " << player_number << " has won!!!\n";
else if (result == 10)
cout << endl << "The AI has won! Better luck next time!\n";
else if (result = -10)
cout << endl << "You beat the world's best AI! Congratulations!\n";
else
cout << endl << "The game has been drawn!" << endl;
return 0;
}
void PrintBoard(array <char, 9> Pos)
{
system("cls");
cout << setw(6) << "|" << setw(6) << "|" << endl << setw(3) << Pos[0] << setw(3) << "|" << setw(3) << Pos[1] << setw(3) << "|" << setw(3) << Pos[2] << " TIC TOE" << endl;
cout << "_____|_____|_____" << endl;
cout << setw(6) << "|" << setw(6) << "|" << endl << setw(3) << Pos[3] << setw(3) << "|" << setw(3) << Pos[4] << setw(3) << "|" << setw(3) << Pos[5] << " TAC " << endl;
cout << "_____|_____|_____" << endl;
cout << setw(6) << "|" << setw(6) << "|" << endl << setw(3) << Pos[6] << setw(3) << "|" << setw(3) << Pos[7] << setw(3) << "|" << setw(3) << Pos[8] << " TIC TOE " << endl;
cout << " | |" << endl;
}
int programprogress()
{
while (k == -11 && AI)
{
bool InvalidChoice = false;
char letter;
//player_number = (player_number % 2) ? 1 : 2;
int PlayerChoice;
if (player_number == 2)
{
cout << endl << "What is your move?" << endl;
cin >> PlayerChoice;
while ((PlayerChoice < 1) || (PlayerChoice > 9))
{
cout << "That's an invalid choice! Please choose a number that is 1-9!" << endl;
cin >> PlayerChoice;
}
PlayerChoice--;
letter = (!first) ? 'X' : 'O';
if (Pos[PlayerChoice] == '1' || Pos[PlayerChoice] == '2' || Pos[PlayerChoice] == '3' || Pos[PlayerChoice] == '4' || Pos[PlayerChoice] == '5' || Pos[PlayerChoice] == '6' || Pos[PlayerChoice] == '7' || Pos[PlayerChoice] == '8' || Pos[PlayerChoice] == '9')
{
Pos[PlayerChoice] = letter;
PrintBoard(Pos);
}
/*else
{
cout << "That space is already taken!" << endl;
player_number--;
}*/
k = checkwin(Pos);
if (k != -11)
k = k * -10;
player_number = 1;
}
else
{
cout << endl << "The computer has made its move!" << endl;
letter = (first) ? 'X' : 'O';
if (first)
PlayerChoice = bestMove(Pos, 1);
else
PlayerChoice = bestMove(Pos, 2);
Pos[PlayerChoice] = letter;
PrintBoard(Pos);
k = checkwin(Pos);
if (k != -11)
k = k * 10;
player_number = 2;
}
}
while (k == -11 && !AI)
{
bool InvalidChoice = false;
char letter;
player_number = (player_number % 2) ? 1 : 2;
int PlayerChoice;
cout << endl << "What's player " << player_number << "'s move?" << endl;
cin >> PlayerChoice;
while ((PlayerChoice < 1) || (PlayerChoice > 9))
{
cout << "That's an invalid choice! Please choose a number that is 1-9!" << endl;
cin >> PlayerChoice;
}
PlayerChoice--;
letter = (player_number == 1) ? 'X' : 'O';
if (Pos[PlayerChoice] == '1' || Pos[PlayerChoice] == '2' || Pos[PlayerChoice] == '3' || Pos[PlayerChoice] == '4' || Pos[PlayerChoice] == '5' || Pos[PlayerChoice] == '6' || Pos[PlayerChoice] == '7' || Pos[PlayerChoice] == '8' || Pos[PlayerChoice] == '9')
{
Pos[PlayerChoice] = letter;
PrintBoard(Pos);
}
else
{
cout << "That space is already taken!" << endl;
player_number--;
}
k = checkwin(Pos);
player_number++;
}
return k;
}
int checkwin(array <char, SIZE> Pos)
{
if (Pos[0] == Pos[1] && Pos[1] == Pos[2])
return 1;
else if (Pos[3] == Pos[4] && Pos[4] == Pos[5])
return 1;
else if (Pos[6] == Pos[7] && Pos[7] == Pos[8])
return 1;
else if (Pos[0] == Pos[3] && Pos[3] == Pos[6])
return 1;
else if (Pos[1] == Pos[4] && Pos[4] == Pos[7])
return 1;
else if (Pos[2] == Pos[5] && Pos[5] == Pos[8])
return 1;
else if (Pos[0] == Pos[4] && Pos[4] == Pos[8])
return 1;
else if (Pos[2] == Pos[4] && Pos[4] == Pos[6])
return 1;
else if (Pos[0] != '1' && Pos[1] != '2' && Pos[2] != '3'
&& Pos[3] != '4' && Pos[4] != '5' && Pos[5] != '6'
&& Pos[6] != '7' && Pos[7] != '8' && Pos[8] != '9')
return 0;
else
return -11;
}
int minimax(array <char, SIZE> newpos, int depth, int player, bool opp)
{
int scale = 0;
if ((player == 1 && first) || (player == 2 && !first))
scale = 10;
else
scale = -10;
//cout << scale;
int score = scale*checkwin(newpos);
if (score < 0)
score += depth;
else if (score > 0)
score -= depth;
if (score == -10 || score == 10 || score == 0)
return score;
if (opp)
{
int best = -1000;
for (int i = 0; i < SIZE; i++)
{
if (newpos[i] != 'X' && newpos[i] != 'O')
{
char temp = newpos[i];
newpos[i] = PlayerSymbol(player);
best = max(best, minimax(newpos, depth + 1, Opposite(player), !opp));
newpos[i] = temp;
}
}
return best;
}
else
{
int best = 1000;
for (int i = 0; i < SIZE; i++)
{
if (newpos[i] != 'X' && newpos[i] != 'O')
{
char temp = newpos[i];
newpos[i] = PlayerSymbol(player);
best = min(best, minimax(newpos, depth + 1, Opposite(player), !opp));
newpos[i] = temp;
}
}
return best;
}
}
int bestMove(array <char, SIZE> newpos, int player)
{
int best = -1000;
int bestpos = -1;
for (int i = 0; i < SIZE; i++)
{
if (newpos[i] != 'X' && newpos[i] != 'O')
{
char temp = newpos[i];
newpos[i] = PlayerSymbol(player);
int move = minimax(newpos, 0, player, !first);
newpos[i] = temp;
if (move > best)
{
//cout << "I like pineapple on pizza" << endl;
bestpos = i;
best = move;
}
/*if (move == best)
{
cout << "I like pineapple on pizza" << endl;
}*/
}
}
cout << bestpos;
return bestpos;
}
int Opposite(int x)
{
if (x == 1)
return 2;
else
return 1;
}
char PlayerSymbol(int x)
{
if (x == 1)
return 'X';
else
return 'O';
}
由于bestpos的值为-1，因此出现越界错误。不过，我不确定如何更改。
答案 0 :(得分：0)
我可以找到4个问题。解决它们似乎可以导致预期的行为。
首先，当您从minimax(newpos, 0, player, !first);函数内部调用bestMove时，您传递的是player而不是Opposite(player)，这表明第一步minimax将是由与bestMove步骤相同的玩家执行。换句话说：AI为自己进行了两次连续动作。因此，player需要更改为Opposite(player)。
第二，minimax有一个名为opp的布尔变量，该变量似乎表明是AI还是它的对手。对于第一个极小极大步骤，opp设置为!first，表示只有在AI首先出现时，对手才会在AI之后移动。那是不对的。在AI之后，总是对手采取行动。因此bestMove应该用minimax而不是true来调用!first。顺便说一句，opp是多余的，因为您可以使用(player == 1 && first) || (player == 2 && !first)来检查它是AI还是对手。
第三，scale的设置方式错误。使用(player == 1 && first) || (player == 2 && !first)，您可以检查其AI是否在移动。但是，在潜在获胜的举动之后，您可以在下一个minimax步骤中进行操作。因此，如果AI采取了行动，并且游戏已经获胜，那么对手做出了获胜的行动，而不是AI。嗯，比例应该是
if ((player == 1 && first) || (player == 2 && !first))
scale = -10;
else
scale = 10;
相反。
最后，您在添加score之后检查depth是10还是-10。如果depth不为0，则此检查将始终失败。因此，深度超过0时，AI只能看到平局，永远不会赢。您可以改写
if (score == -10 || score == 10 || score == 0)
{
if (score < 0)
score += depth;
else if (score > 0)
score -= depth;
return score;
}
希望这可以完全回答您的问题。