Алгоритм минимакса не работает должным образом (реализован на C)

У меня возникла проблема с реализацией минимаксного алгоритма в C для игры в крестики-нолики, вот код для функции minimax():

int minimax(char(*board)[3], int isMax, char var)
{
    int score;
    char oppVar;
    int maxScore = -1000;
    int minScore = 1000;

    if (var == 'X')
        oppVar = 'O';
    else
        oppVar = 'X';

    if (checkWnr(board, var))
        return 1;
    else if (var == 'O' && checkWnr(board, oppVar)) //the condition without which the program doesn't run properly
        return -1;                                  //details lower in the post
    else if (!emptyCells(board))
        return 0;

    if (isMax)
    {
        for (int i = 0; i < 3; i++)
            for (int j = 0; j < 3; j++)
                if (board[i][j] == ' ')
                {
                    board[i][j] = var;
                    score = minimax(board, 0, oppVar);
                    maxScore = max(maxScore, score);
                    board[i][j] = ' ';
                }
        return maxScore;
    }
    else
    {
        for (int i = 0; i < 3; i++)
            for (int j = 0; j < 3; j++)
                if (board[i][j] == ' ')
                {
                    board[i][j] = var;
                    score = minimax(board, 1, oppVar);
                    minScore = min(minScore, score);
                    board[i][j] = ' ';
                }
        return minScore;
    }

Функция, которая вызывает его и фактически делает ход на доске:

void bestMove(int dum1, int dum2, char(*board)[3], char var)
{
    int score;
    MOVES move;
    move.grade = -1000;
    char oppVar;

    if (var == 'X')
        oppVar = 'O';
    else
        oppVar = 'X';

    for (int i = 0; i < 3; i++)
        for (int j = 0; j < 3; j++)
            if (board[i][j] == ' ')
            {
                board[i][j] = var;
                score = minimax(board, 0, oppVar);
                if (score > move.grade)
                {
                    move.grade = score;
                    move.line = i;
                    move.column = j;
                }
                board[i][j] = ' ';
            }
    board[move.line][move.column] = var;
}

а также структуру MOVES и функции checkWnr(), emptyCells(), использованные выше:

typedef struct {
    int line;
    int column;
    int grade;
}MOVES;


int checkWnr(char(*board)[3], char var)
{
    if (board[0][0] == var && board[1][1] == var && board[2][2] == var)
        return 1;
    else if (board[0][2] == var && board[1][1] == var && board[2][0] == var)
        return 1;
    for (int i = 0; i < 3; i++)
        if (board[i][0] == var && board[i][1] == var && board[i][2] == var)
            return 1;
        else if (board[0][i] == var && board[1][i] == var && board[2][i] == var)
return 1;
    return 0;
}

int emptyCells(char(*board)[3])
{
    int nr = 0;
    for (int i = 0; i < 3; i++)
        for (int j = 0; j < 3; j++)
            if (board[i][j] == ' ')
                nr++;
    return nr;
}

В основном алгоритм работает по назначению только при соблюдении следующего условия (для возврата -1 при убытке):

else if (var == 'O' && checkWnr(board, oppVar)) return -1;

если я, например, удалю условие var == 'O' или добавлю другое, аналогичное для «X», например:

else if (var == 'X' && checkWnr(board, oppVar)) return -1;

все время, ОСТАВЛЯЯ другой на месте, программа по-прежнему будет размещать значения на доске слева направо, не обращая внимания на полученные баллы.

Я понятия не имею, почему это происходит, любая помощь будет оценена, спасибо заранее!

Компилируемый код:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <windows.h>

#define PLAYR 1
#define COMPR 2

typedef struct {
    int line;
    int column;
    int grade; }MOVES;

void clearBoard(char(*board)[3]); void showBoard(char(*board)[3]); int valid(int line, int col, char(*board)[3]); void usrMove(int line, int col, char(*board)[3], char var); int checkWnr(char(*board)[3], char var); int winner(char(*board)[3], char p1var, char p2var); int emptyCells(char(*board)[3]); void getInput(int* line, int* col, char(*board)[3]); void bestMove(int dum1, int dum2, char(*board)[3], char var); int minimax(char(*board)[3], int isMax, char var);

int main() {
    char board[3][3], input[10], p1var, p2var;
    int line, col;

    while (1)
    {
        do
        {
            printf("\n(P1) X or O? ");
            fseek(stdin, 0, SEEK_END);
            fgets(input, 10, stdin);
            input[strcspn(input, "\n")] = 0;
            input[0] = toupper(input[0]);
        } while (strcmp(input, "X") && strcmp(input, "O"));
        if (!strcmp(input, "X"))
        {
            p1var = 'X';
            p2var = 'O';
        }
        else
        {
            p1var = 'O';
            p2var = 'X';
        }
        clearBoard(board);
        system("cls");
        while (!winner(board, p1var, p2var) && emptyCells(board))
        {
            showBoard(board);
            getInput(&line, &col, board);
            line--; col--;
            usrMove(line, col, board, p1var);
            if (!emptyCells(board) || winner(board, p1var, p2var))
            {
                system("cls");
                break;
            }
            bestMove(line, col, board, p2var);
            system("cls");
        }
        showBoard(board);
        if (winner(board, p1var, p2var) == PLAYR)
                printf("\nYou won!");
        else if (winner(board, p1var, p2var) == COMPR)
                printf("\nYou lost!");
        else if (!emptyCells(board))
            printf("\nTie!");
    }

    return 0; }

int valid(int line, int col, char(*board)[3]) {
    if (line > 3 || line < 1 || col > 3 || col < 1 || board[line - 1][col - 1] != ' ')
        return 0;
    return 1; }

void getInput(int* line, int* col, char(*board)[3]) {
    do
    {
        printf("\nEnter line, column: ");
        fseek(stdin, 0, SEEK_END);
        scanf_s("%d %d", line, col);
        if (!valid((*line), (*col), board))
        {
            printf("\nInvalid input, please try again!");
            (*line) = -1;
            (*col) = -1;
        }
    } while (!valid((*line), (*col), board)); }

int winner(char(*board)[3], char p1var, char p2var) {
    if (checkWnr(board, p1var))
        return PLAYR;
    else if (checkWnr(board, p2var))
        return COMPR;
    return 0; }

void usrMove(int line, int col, char(*board)[3], char var) {
    board[line][col] = var;
    return 0; }

void clearBoard(char(*board)[3]) {
    for (int i = 0; i < 3; i++)
        for (int j = 0; j < 3; j++)
            *(*(board + i) + j) = ' '; }

void showBoard(char(*board)[3]) {
    printf("\n|---|---|---|\n");
    printf("| %c | %c | %c |\n", board[0][0], board[0][1], board[0][2]);
    printf("|---|---|---|\n");
    printf("| %c | %c | %c |\n", board[1][0], board[1][1], board[1][2]);
    printf("|---|---|---|\n");
    printf("| %c | %c | %c |\n", board[2][0], board[2][1], board[2][2]);
    printf("|---|---|---|\n"); }

int checkWnr(char(*board)[3], char var) {
    if (board[0][0] == var && board[1][1] == var && board[2][2] == var)
        return 1;
    else if (board[0][2] == var && board[1][1] == var && board[2][0] == var)
        return 1;
    for (int i = 0; i < 3; i++)
        if (board[i][0] == var && board[i][1] == var && board[i][2] == var)
            return 1;
        else if (board[0][i] == var && board[1][i] == var && board[2][i] == var)
            return 1;
    return 0; }

int emptyCells(char(*board)[3]) {
    int nr = 0;
    for (int i = 0; i < 3; i++)
        for (int j = 0; j < 3; j++)
            if (board[i][j] == ' ')
                nr++;
    return nr; }

void bestMove(int dum1, int dum2, char(*board)[3], char var) {
    int score;
    MOVES move;
    move.grade = -1000;
    char oppVar;

    if (var == 'X')
        oppVar = 'O';
    else
        oppVar = 'X';

    for (int i = 0; i < 3; i++)
        for (int j = 0; j < 3; j++)
            if (board[i][j] == ' ')
            {
                board[i][j] = var;
                score = minimax(board, 0, oppVar);
                if (score > move.grade)
                {
                    move.grade = score;
                    move.line = i;
                    move.column = j;
                }
                board[i][j] = ' ';
            }
    board[move.line][move.column] = var; }

int minimax(char(*board)[3], int isMax, char var) {
    int score;
    char oppVar;
    int maxScore = -1000;
    int minScore = 1000;

    if (var == 'X')
        oppVar = 'O';
    else
        oppVar = 'X';

    if (checkWnr(board, var))
        return 1;
    else if (var == 'O' && checkWnr(board, oppVar))
        return -1;
    else if (!emptyCells(board))
        return 0;

    if (isMax)
    {
        for (int i = 0; i < 3; i++)
            for (int j = 0; j < 3; j++)
                if (board[i][j] == ' ')
                {
                    board[i][j] = var;
                    score = minimax(board, 0, oppVar);
                    maxScore = max(maxScore, score);
                    board[i][j] = ' ';
                }
        return maxScore;
    }
    else
    {
        for (int i = 0; i < 3; i++)
            for (int j = 0; j < 3; j++)
                if (board[i][j] == ' ')
                {
                    board[i][j] = var;
                    score = minimax(board, 1, oppVar);
                    minScore = min(minScore, score);
                    board[i][j] = ' ';
                }
        return minScore;
    } }