Untitled

#define ROW_SIZE 9
#define COL_SIZE 9

// return true if its valid set, return false if we've seen a duplicate
bool validateSet(uint32_t* current_set, char new_val) {
    int number = new_val - '1';  // "5" - "1" = 4 (more of an index)
    
    bool seen = (*current_set >> number) & 0x1; // 0x000010000 >> 4 = 0x1
    
    // 0x000000000 | 0x000010000 = 0x000010000
    *current_set = *current_set | (0x1 << number); // 0x000010000 = 1 << 4
    
    return !seen;
}

bool isColumnValid (char **board, int col_number) {
    uint32_t set = 0x000000000;
    
    for (int i = 0; i < COL_SIZE; i++) {
        char current_num = board[i][col_number]; // 5, 3, ., .
        
        if (current_num == '.') continue;
        bool is_valid = validateSet(&set, current_num);
        
        if (!is_valid) return false;
    }
    
    return true;
}

bool isRowValid(char** board, int row_number) {
    uint32_t set = 0x000000000;
    for (int i = 0; i < ROW_SIZE; i++) {
        char current_num = board[row_number][i]; // 5, 3, ., .
        
        if (current_num == '.') continue;
        bool is_valid = validateSet(&set, current_num);
        
        if (!is_valid) return false;
    }
    
    return true;
}

bool isSquareValid(char** board, int square_number) {
    // First, find the starting indices of the square
    // 0 -> 0,0; 1 -> 0,3; 2 -> 0,6
    // 3 -> 3,0; 4 -> 3,3; 5 -> 3,6
    // 6 -> 6,0; 7 -> 6,3; 8 -> 6,6
    
    uint32_t set = 0x000000000;
    int row = square_number - (square_number % 3), col = (square_number % 3) * 3;
    
    for (int i = row; i <= row + 2; i++) {
        for (int j = col; j <= col + 2; j++) {
            char current_num = board[i][j]; // 5, 3, ., .

            if (current_num == '.') continue;
            bool is_valid = validateSet(&set, current_num);    
            
            if (!is_valid) return false;
        }
    }
    
    return true;
}

bool isValidSudoku(char** board, int boardSize, int* boardColSize){
    for (int i = 0; i < ROW_SIZE; i++) {
        bool valid_col = isColumnValid(board, i);
        bool valid_row = isRowValid(board, i);
        bool valid_square = isSquareValid(board, i);
        
        if (!(valid_col & valid_row & valid_square)) return false;
    }
    return true;
}