I'm trying to make a simple game where a building placed in a nested list must be next to another building. The problem I face is that if the building was placed at the sides, I can't use for loops to check for existing buildings since it would not be part of the list anymore, since there is nothing on some sides of the building.

board = [['', '', '', ''],['', '', '', ''],['', '', '', ''],['', '', '', '']]building_list = ['HSE', 'FAC', 'SHP', 'HWY', 'BCH']

Output:

Turn 2A     B     C     D+-----+-----+-----+-----+
1|     |     |     |     |+-----+-----+-----+-----+
2|     | HSE |     |     |+-----+-----+-----+-----+
3|     |     |     |     |+-----+-----+-----+-----+
4|     |     |     |     |+-----+-----+-----+-----+
1. Build a HWY
2. Build a HWY
3. See remaining buildings
4. See current score5. Save game
0. Exit to main menu
Your choice? 1
Build where? a3
You must build next to an existing building.

My current code:

def build_buildings():global turna = 0m = 1j = 1k = 1i = 1if option == 1:building = option1else:building = option2location = input('Build where? ')location.split()col = location[0]row = int(location[1]) - 1if col == 'a':col = 0elif col == 'b':col = 1elif col == 'c':col = 2else:col = 3if turn > 1:if col == 0:m = -1if row == 0:j = 0if col == 3:k = -1if row == 3:i = 0if (board[int(row + i)][col] or board[int(row - j)][col] or board[int(row)][col + k]or board[int(row)][col - m]) != '':board[int(row)][col] = buildingelse:board[int(row)][col] = ''print('You must build next to an existing building.')print()turn -= 1else:board[int(row)][col] = building

Try this code:

def build(place: str, what: int, first_build: bool = False):if len(place) == 2 and 0 <= what < len(building_list):  # check the argumentsx, y = x_axe.get(place[0].upper(), -1), int(place[1]) if place[1].isdigit() else -1  # get the x,y coordinates# check the conditions to buildif 0 <= x <= width and 0 <= y <= height and board[y][x] == '' and \(first_build or any(0 <= x + dx <= width and 0 <= y + dy <= height and board[y + dy][x + dx] != '' for dy, dx in((-1, 0), (0, 1), (1, 0), (0, -1)))):board[y][x] = building_list[what]  # build!# global variables
board = [['', '', '', ''],['', '', '', ''],['', '', '', ''],['', '', '', '']]
building_list = ['HSE', 'FAC', 'SHP', 'HWY', 'BCH']
x_axe = {'A': 0, 'B': 1, 'C': 2, 'D': 3}  # make dict with x indexes for use in build()
# get the max coordinates of the board
height = len(board) - 1
width = len(board[0]) - 1# simple examples; replace with your code
build('a3', 0, True)  # first build with True as third argument
build('b3', 1)  # other buildings; will be built
build('d3', 2)  # will not be built because of conditions
build('B2', 2)  # will be built
build('S9', 3)  # will not be built due to wrong symbol and wrong y coordinate# output the board. first, make the format strings for the table
line = f"  {'+-----' * (width + 1)}+"  # +-----+-----+-----+-----+
row = f" {'|{:^5}' * (width + 1)}|"  # |{:^5}|{:^5}|{:^5}|{:^5}|
header = f"   {'{:^6}' * (width + 1)}"  # {:^6}{:^6}{:^6}{:^6}
print(header.format(*x_axe.keys()), line, sep='\n')  # header
for i in range(height + 1):print(str(i) + row.format(*board[i]), line, sep='\n')

Output:

     A     B     C     D   +-----+-----+-----+-----+
0 |     |     |     |     |+-----+-----+-----+-----+
1 |     |     |     |     |+-----+-----+-----+-----+
2 |     | SHP |     |     |+-----+-----+-----+-----+
3 | HSE | FAC |     |     |+-----+-----+-----+-----+