The tester for Python works poorly


Unfortunately I couldn’t submit a correct solution since it wasn’t clear which output should be retrieved or printed when submitting the code in Python. After about 10 minutes of trying several formatting, I gave up and looked at the solution. I lost all points even though I solved the original problem in less than 20 minutes.

However, the main purpose of this message is for you to update the tester.

My solution is attached:
import uuid

class Solution:
# @param A : list of list of chars
def solve(self, A):
A = [list(s) for s in A]

    n = len(A)
    m = len(A[0])
    visited = set()
    islands = {}
    valid_regions = {}

    for i in range(n):
        for j in range(m):
            if A[i][j] == 'O' and (i, j) not in visited:
                island_id = str(uuid.uuid4())
                islands[island_id] = set([(i ,j)])
                valid_regions[island_id] = True

                stack = [(i, j)]
                while stack:
                    curr_i, curr_j = stack.pop()
                    if 0 <= curr_i < n and 0 <= curr_j < m:
                        if curr_i == 0 or curr_i == n-1 or curr_j == 0 or curr_j == m-1:
                            if A[curr_i][curr_j] == 'O':
                                valid_regions[island_id] = False

                        if A[curr_i][curr_j] == 'O':
                            islands[island_id].add((curr_i, curr_j))

                            for d1 in range(-1, 2):
                                for d2 in range(-1, 2):
                                    if abs(d1) + abs(d2) <= 1:
                                        expand_i = curr_i + d1
                                        expand_j = curr_j + d2
                                        if (expand_i, expand_j) not in visited:
                                            visited.add((expand_i, expand_j))
                                            stack.append((expand_i, expand_j))

    for island_id in islands:
        if valid_regions[island_id]:
            for i, j in islands[island_id]:
                A[i][j] = 'X'

    return [''.join(s) for s in A]