Buggy python submission (verdict: Time Limit Exceeded):
from collections import deque

def penetrate(x, y, count):
    global max_idx
    for i in range(4):
        nx = x + dx[i]
        ny = y + dy[i]

        if 0 <= nx < h and 0 <= ny < w and A[nx][ny] == "." and d[nx][ny] == -1:
            d[nx][ny] = count + 1
            q.append((nx, ny, d[nx][ny]))
            max_idx = max(max_idx, d[nx][ny])


h, w = map(int, input().split())
d = [[-1] * w for _ in range(h)]

A = [[] for i in range(h)]
q = deque()

for i in range(h):
    A[i] = list(input())
    for j in range(w):
        if A[i][j] == "#":
            d[i][j] = 0
            q.append((i, j, d[i][j]))

dx = [1, 0, -1, 0]
dy = [0, 1, 0, -1]
max_idx = 0

while len(q) > 0:
    idx = q.popleft()
    penetrate(idx[0], idx[1], idx[2])

print(max_idx)

Fixed submission:
from collections import deque

def penetrate(x, y, count):
    global max_idx
    for i in range(4):
        nx = x + dx[i]
        ny = y + dy[i]

        if 0 <= nx < h and 0 <= ny < w and A[nx][ny] == "." and d[nx][ny] == -1:
            d[nx][ny] = count + 1
            q.append((nx, ny, d[nx][ny]))
            max_idx = max(max_idx, d[nx][ny])


h, w = map(int, input().split())
d = [[-1] * w for _ in range(h)]

A = [[] for i in range(h)]
q = deque()

for i in range(h):
    A[i] = list(input())
    for j in range(w):
        if A[i][j] == "#":
            d[i][j] = 0
            q.append((i, j, d[i][j]))

dx = [1, 0, -1, 0]
dy = [0, 1, 0, -1]
max_idx = 0

while len(q) > 0:
    idx = q.popleft()
    penetrate(idx[0], idx[1], idx[2])

print(max_idx)

Buggy python submission (verdict: Time Limit Exceeded):
import queue

def penetrate(x, y, count):
    global max_idx
    for i in range(4):
        nx = x + dx[i]
        ny = y + dy[i]

        if 0 <= nx < h and 0 <= ny < w and A[nx][ny] == "." and d[nx][ny] == -1:
            d[nx][ny] = count + 1
            q.put((nx, ny, d[nx][ny]))
            max_idx = max(max_idx, d[nx][ny])


h, w = map(int, input().split())
d = [[-1] * w for _ in range(h)]

A = [[] for i in range(h)]
q = queue.Queue()

for i in range(h):
    A[i] = list(input())
    for j in range(w):
        if A[i][j] == "#":
            d[i][j] = 0
            q.put((i, j, d[i][j]))

dx = [1, 0, -1, 0]
dy = [0, 1, 0, -1]
max_idx = 0

while q.empty() == False:
    idx = q.get()
    penetrate(idx[0], idx[1], idx[2])

print(max_idx)


Fixed submission:
from collections import deque

def penetrate(x, y, count):
    global max_idx
    for i in range(4):
        nx = x + dx[i]
        ny = y + dy[i]

        if 0 <= nx < h and 0 <= ny < w and A[nx][ny] == "." and d[nx][ny] == -1:
            d[nx][ny] = count + 1
            q.append((nx, ny, d[nx][ny]))
            max_idx = max(max_idx, d[nx][ny])


h, w = map(int, input().split())
d = [[-1] * w for _ in range(h)]

A = [[] for i in range(h)]
q = deque()

for i in range(h):
    A[i] = list(input())
    for j in range(w):
        if A[i][j] == "#":
            d[i][j] = 0
            q.append((i, j, d[i][j]))

dx = [1, 0, -1, 0]
dy = [0, 1, 0, -1]
max_idx = 0

while len(q) > 0:
    idx = q.popleft()
    penetrate(idx[0], idx[1], idx[2])

print(max_idx)

Buggy python submission (verdict: Time Limit Exceeded):
import queue
import numpy as np

def penetrate(x, y, count):
    for i in range(4):
        nx = x + dx[i]
        ny = y + dy[i]

        if 0 <= nx < h and 0 <= ny < w and A[nx][ny] == "." and d[nx][ny] == -1:
            d[nx][ny] = count + 1
            q.put((nx, ny, d[nx][ny]))


h, w = map(int, input().split())
d = [[-1] * w for _ in range(h)]

A = [[] for i in range(h)]
q = queue.Queue()

for i in range(h):
    A[i] = list(input())
    for j in range(w):
        if A[i][j] == "#":
            d[i][j] = 0
            q.put((i, j, d[i][j]))

dx = [1, 0, -1, 0]
dy = [0, 1, 0, -1]

while q.empty() == False:
    idx = q.get()
    penetrate(idx[0], idx[1], idx[2])

print(np.max(d))


Fixed submission:
from collections import deque

def penetrate(x, y, count):
    global max_idx
    for i in range(4):
        nx = x + dx[i]
        ny = y + dy[i]

        if 0 <= nx < h and 0 <= ny < w and A[nx][ny] == "." and d[nx][ny] == -1:
            d[nx][ny] = count + 1
            q.append((nx, ny, d[nx][ny]))
            max_idx = max(max_idx, d[nx][ny])


h, w = map(int, input().split())
d = [[-1] * w for _ in range(h)]

A = [[] for i in range(h)]
q = deque()

for i in range(h):
    A[i] = list(input())
    for j in range(w):
        if A[i][j] == "#":
            d[i][j] = 0
            q.append((i, j, d[i][j]))

dx = [1, 0, -1, 0]
dy = [0, 1, 0, -1]
max_idx = 0

while len(q) > 0:
    idx = q.popleft()
    penetrate(idx[0], idx[1], idx[2])

print(max_idx)

Buggy python submission (verdict: Time Limit Exceeded):
import numpy as np

def penetrate(x, y, idx):
    for i in range(4):
        nx = x + dx[i]
        ny = y + dy[i]

        if 0 <= nx < h and 0 <= ny < w and A[nx][ny] == "." and d[nx][ny] == -1:
            d[nx][ny] = idx + 1


h, w = map(int, input().split())
d = [[-1] * w for _ in range(h)]

A = [[] for i in range(h)]

for i in range(h):
    A[i] = list(input())
    for j in range(w):
        if A[i][j] == "#":
            d[i][j] = 0

dx = [1, 0, -1, 0]
dy = [0, 1, 0, -1]

idx = 0
while True:
    count = 0
    for i in range(h):
        for j in range(w):
            if d[i][j] == idx:
                penetrate(i, j, idx)
            if d[i][j] == -1:
                count += 1
    idx += 1
    if count == 0:
        break

print(np.max(d))


Fixed submission:
from collections import deque

def penetrate(x, y, count):
    global max_idx
    for i in range(4):
        nx = x + dx[i]
        ny = y + dy[i]

        if 0 <= nx < h and 0 <= ny < w and A[nx][ny] == "." and d[nx][ny] == -1:
            d[nx][ny] = count + 1
            q.append((nx, ny, d[nx][ny]))
            max_idx = max(max_idx, d[nx][ny])


h, w = map(int, input().split())
d = [[-1] * w for _ in range(h)]

A = [[] for i in range(h)]
q = deque()

for i in range(h):
    A[i] = list(input())
    for j in range(w):
        if A[i][j] == "#":
            d[i][j] = 0
            q.append((i, j, d[i][j]))

dx = [1, 0, -1, 0]
dy = [0, 1, 0, -1]
max_idx = 0

while len(q) > 0:
    idx = q.popleft()
    penetrate(idx[0], idx[1], idx[2])

print(max_idx)

Buggy python submission (verdict: Runtime Error):
import numpy as np

def penetrate(x, y, idx):
    for i in range(4):
        nx = x + dx[i]
        ny = y + dy[i]

        if 0 <= nx < h and 0 <= ny < w and A[nx][ny] == "." and d[nx][ny] == -1:
            d[nx][ny] = idx + 1


h, w = map(int, input().split())
d = [[-1] * w for _ in range(h)]

A = [[] for i in range(h)]

for i in range(h):
    A[i] = list(input())
    for j in range(w):
        if A[i][j] == "#":
            d[i][j] = 0

dx = [1, 0, -1, 0]
dy = [0, 1, 0, -1]

idx = 0
while True:
    count = 0
    for i in range(h):
        for j in range(w):
            if d[i][j] == idx:
                penetrate(i, j, idx)
            if d[i][j] == -1:
                count += 1
    idx += 1
    if count == 0:
        break

print(np.max(d))


Fixed submission:
from collections import deque

def penetrate(x, y, count):
    global max_idx
    for i in range(4):
        nx = x + dx[i]
        ny = y + dy[i]

        if 0 <= nx < h and 0 <= ny < w and A[nx][ny] == "." and d[nx][ny] == -1:
            d[nx][ny] = count + 1
            q.append((nx, ny, d[nx][ny]))
            max_idx = max(max_idx, d[nx][ny])


h, w = map(int, input().split())
d = [[-1] * w for _ in range(h)]

A = [[] for i in range(h)]
q = deque()

for i in range(h):
    A[i] = list(input())
    for j in range(w):
        if A[i][j] == "#":
            d[i][j] = 0
            q.append((i, j, d[i][j]))

dx = [1, 0, -1, 0]
dy = [0, 1, 0, -1]
max_idx = 0

while len(q) > 0:
    idx = q.popleft()
    penetrate(idx[0], idx[1], idx[2])

print(max_idx)