Buggy python submission (verdict: Runtime Error):
from collections import deque

def bfs(que,d): #幅優先探索
  "
  #いつもはここで定義
  #入力のグラフを初期化
  #d = [[float("inf")] * w for i in range(h)] 
  #que = deque([])
  #que.append((sx,sy))
  #d[sx][sy] = 0
  "
  lead = 0
  dx = [-1,0,0,1]
  dy = [0,-1,1,0]
  
  while que:
    lead_h,lead_w = que.popleft()
    lead = d[lead_h][lead_w]
    #lead == queの先頭にある要素を取り出す
    for i in range(4):
      nx = lead_w + dx[i]
      ny = lead_h + dy[i]
      if ny<0 or h<=ny or nx<0 or w<=nx:
        #範囲外の場合
        continue
      if d[ny][nx]==float("inf"):
        d[ny][nx] = lead + 1
        que.append((ny,nx))
  return lead

h, w = map(int, input().split())
maze = [list(input()) for i in range(h)]

#多点スタートなのでbfs()内で定義して初期化しない
d = [[float("inf")] * w for i in range(h)] 

#キューも同様
que = deque([])
for i in range(h):
  for j in range(w):
    if maze[i][j] == "#":
      que.append((i,j))
      #各"#"を入れる
      d[i][j] = 0

#print(bfs())
lead = bfs(que,d)
print(lead)

Fixed submission:
from collections import deque

H, W = map(int, input().split())
grid = [input() for i in range(H)]

# 初期の黒('#')の位置からの距離
dist = [[-1]*W for _ in range(H)]

# '#'の位置をキューに追加（＝今回はこれが複数あるので、複数スタートとなる）
black_cells = deque()
for h in range(H):
    for w in range(W):
        if grid[h][w] == '#':
            black_cells.append((h, w))
            dist[h][w] = 0

def bfs(black_cells, dist):
    d = 0
    while black_cells:
        # キューとして使うのでpop()ではなくpopleft()
        h, w = black_cells.popleft()
        d = dist[h][w]
        for dy, dx in ((1, 0), (0, 1), (-1, 0), (0, -1)):
            new_h = h + dy
            new_w = w + dx
            if new_h < 0 or H <= new_h or new_w < 0 or W <= new_w:
                continue
            if dist[new_h][new_w] == -1:  # セルが白('.')であるのと同義
                dist[new_h][new_w] = d+1
                black_cells.append((new_h, new_w))
    return d

d = bfs(black_cells, dist)
print(d)

Buggy python submission (verdict: Runtime Error):
from collections import deque

def bfs(que,d): #幅優先探索
  "
  #いつもはここで定義
  #入力のグラフを初期化
  #d = [[float("inf")] * w for i in range(h)] 
  #que = deque([])
  #que.append((sx,sy))
  #d[sx][sy] = 0
  "
  dx = [-1,0,0,1]
  dy = [0,-1,1,0]
  
  while que:
    lead_h,lead_w = que.popleft()
    lead = d[lead_h][lead_w]
    #lead == queの先頭にある要素を取り出す
    for i in range(4):
      nx = lead_w + dx[i]
      ny = lead_h + dy[i]
      if ny<0 or h<=ny or nx<0 or w<=nx:
        #範囲外の場合
        continue
      if d[ny][nx]==float("inf"):
        d[ny][nx] = lead + 1
        que.append((ny,nx))
  return lead

h, w = map(int, input().split())
maze = [list(input()) for i in range(h)]

#多点スタートなのでbfs()内で定義して初期化しない
d = [[float("inf")] * w for i in range(h)] 

#キューも同様
que = deque([])
for i in range(h):
  for j in range(w):
    if maze[i][j] == "#":
      que.append((i,j))
      #各"#"を入れる
      d[i][j] = 0

#print(bfs())
lead = bfs(que,d)
print(lead)

Fixed submission:
from collections import deque

H, W = map(int, input().split())
grid = [input() for i in range(H)]

# 初期の黒('#')の位置からの距離
dist = [[-1]*W for _ in range(H)]

# '#'の位置をキューに追加（＝今回はこれが複数あるので、複数スタートとなる）
black_cells = deque()
for h in range(H):
    for w in range(W):
        if grid[h][w] == '#':
            black_cells.append((h, w))
            dist[h][w] = 0

def bfs(black_cells, dist):
    d = 0
    while black_cells:
        # キューとして使うのでpop()ではなくpopleft()
        h, w = black_cells.popleft()
        d = dist[h][w]
        for dy, dx in ((1, 0), (0, 1), (-1, 0), (0, -1)):
            new_h = h + dy
            new_w = w + dx
            if new_h < 0 or H <= new_h or new_w < 0 or W <= new_w:
                continue
            if dist[new_h][new_w] == -1:  # セルが白('.')であるのと同義
                dist[new_h][new_w] = d+1
                black_cells.append((new_h, new_w))
    return d

d = bfs(black_cells, dist)
print(d)

Buggy python submission (verdict: Runtime Error):
from collections import deque

def bfs(que,d): #幅優先探索
  #入力のグラフを初期化
  #d = [[float("inf")] * w for i in range(h)] 
  #d == mazeリストの"."を"inf"に変えたリスト
  lead = 0
  dx = [-1,0,0,1]
  dy = [0,-1,1,0]
  
  #que = deque([])
  #que.append((sx,sy))
  #d[sx][sy] = 0
  
  while que:
    lead_h,lead_w = que.popleft()
    lead = d[lead_h][lead_w]
    #lead == queの先頭にある要素を取り出す
    for i in range(4):
      nx = lead_w + dx[i]
      ny = lead_h + dy[i]
      if ny<0 or h<=ny or nx<0 or w<=nx:
        continue
      if d[nx][ny]==float("inf"):
        d[nx][ny] = lead + 1
        que.append((nx,ny))
  return lead

h, w = map(int, input().split())
maze = [list(input()) for i in range(h)]

d = [[float("inf")] * w for i in range(h)] 

que = deque([])
for i in range(h):
  for j in range(w):
    if maze[i][j] == "#":
      que.append((i,j))
      d[i][j] = 0

#print(bfs())
lead = bfs(que,d)
print(lead)

Fixed submission:
from collections import deque

H, W = map(int, input().split())
grid = [input() for i in range(H)]

# 初期の黒('#')の位置からの距離
dist = [[-1]*W for _ in range(H)]

# '#'の位置をキューに追加（＝今回はこれが複数あるので、複数スタートとなる）
black_cells = deque()
for h in range(H):
    for w in range(W):
        if grid[h][w] == '#':
            black_cells.append((h, w))
            dist[h][w] = 0

def bfs(black_cells, dist):
    d = 0
    while black_cells:
        # キューとして使うのでpop()ではなくpopleft()
        h, w = black_cells.popleft()
        d = dist[h][w]
        for dy, dx in ((1, 0), (0, 1), (-1, 0), (0, -1)):
            new_h = h + dy
            new_w = w + dx
            if new_h < 0 or H <= new_h or new_w < 0 or W <= new_w:
                continue
            if dist[new_h][new_w] == -1:  # セルが白('.')であるのと同義
                dist[new_h][new_w] = d+1
                black_cells.append((new_h, new_w))
    return d

d = bfs(black_cells, dist)
print(d)

Buggy python submission (verdict: Runtime Error):
from collections import deque

def bfs(): #幅優先探索
  #入力のグラフを初期化
  #d = [[float("inf")] * w for i in range(h)] 
  #d == mazeリストの"."を"inf"に変えたリスト
  lead = 0
  dx = [-1,0,0,1]
  dy = [0,-1,1,0]
  
  #que = deque([])
  #que.append((sx,sy))
  #d[sx][sy] = 0
  
  while que:
    lead_h,lead_w = que.popleft()
    lead = d[lead_h][lead_w]
    #lead == queの先頭にある要素を取り出す
    for i in range(4):
      nx = lead_w + dx[i]
      ny = lead_h + dy[i]
      if ny<0 or h<=ny or nx<0 or w<=nx:
        continue
      if d[nx][ny]==float("inf"):
        d[nx][ny] = lead + 1
        que.append((nx,ny))
  return lead

h, w = map(int, input().split())
maze = [list(input()) for i in range(h)]

d = [[float("inf")] * w for i in range(h)] 

que = deque([])
for i in range(h):
  for j in range(w):
    if maze[i][j] == "#":
      que.append((i,j))
      d[i][j] = 0

print(bfs())

Fixed submission:
from collections import deque

H, W = map(int, input().split())
grid = [input() for i in range(H)]

# 初期の黒('#')の位置からの距離
dist = [[-1]*W for _ in range(H)]

# '#'の位置をキューに追加（＝今回はこれが複数あるので、複数スタートとなる）
black_cells = deque()
for h in range(H):
    for w in range(W):
        if grid[h][w] == '#':
            black_cells.append((h, w))
            dist[h][w] = 0

def bfs(black_cells, dist):
    d = 0
    while black_cells:
        # キューとして使うのでpop()ではなくpopleft()
        h, w = black_cells.popleft()
        d = dist[h][w]
        for dy, dx in ((1, 0), (0, 1), (-1, 0), (0, -1)):
            new_h = h + dy
            new_w = w + dx
            if new_h < 0 or H <= new_h or new_w < 0 or W <= new_w:
                continue
            if dist[new_h][new_w] == -1:  # セルが白('.')であるのと同義
                dist[new_h][new_w] = d+1
                black_cells.append((new_h, new_w))
    return d

d = bfs(black_cells, dist)
print(d)

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

H, W = map(int, input().split())
grid = [input() for i in range(H)]

# 初期の黒('#')の位置からの距離
dist = [[-1]*W for _ in range(H)]

# '#'の位置をキューに追加（＝今回はこれが複数あるので、複数スタートとなる）
black_cells = deque()
for h in range(H):
    for w in range(W):
        if grid[h][w] == '#':
            black_cells.append((h, w))
            dist[h][w] = 0

def bfs(black_cells, dist):
    d = 0
    while black_cells:
        # キューとして使うのでpop()ではなくpopleft()
        h, w = black_cells.popleft()
        d = dist[h][w]
        for dy, dx in ((1, 0), (0, 1), (-1, 0), (0, -1)):
            new_h = h + dy
            new_w = w + dx
            if new_h < 0 or H <= new_h or new_w < 0 or W <= new_w:
                continue
            if dist[new_h][new_w] == -1:  # セルが白('.')であるのと同義
                dist[new_h][new_w] = d+1
                black_cells.append((new_h, new_w))
    return d

d = bfs(black_cells, dist)
print(d)

Fixed submission:
from collections import deque

H, W = map(int, input().split())
grid = [input() for i in range(H)]

# 初期の黒('#')の位置からの距離
dist = [[-1]*W for _ in range(H)]

# '#'の位置をキューに追加（＝今回はこれが複数あるので、複数スタートとなる）
black_cells = deque()
for h in range(H):
    for w in range(W):
        if grid[h][w] == '#':
            black_cells.append((h, w))
            dist[h][w] = 0

def bfs(black_cells, dist):
    d = 0
    while black_cells:
        # キューとして使うのでpop()ではなくpopleft()
        h, w = black_cells.popleft()
        d = dist[h][w]
        for dy, dx in ((1, 0), (0, 1), (-1, 0), (0, -1)):
            new_h = h + dy
            new_w = w + dx
            if new_h < 0 or H <= new_h or new_w < 0 or W <= new_w:
                continue
            if dist[new_h][new_w] == -1:  # セルが白('.')であるのと同義
                dist[new_h][new_w] = d+1
                black_cells.append((new_h, new_w))
    return d

d = bfs(black_cells, dist)
print(d)

Buggy python submission (verdict: Runtime Error):
from collections import deque

def bfs(): #幅優先探索
  #入力のグラフを初期化
  #d = [[float("inf")] * w for i in range(h)] 
  #d == mazeリストの"."を"inf"に変えたリスト
  dx = [-1,0,0,1]
  dy = [0,-1,1,0]
  
  #que = deque([])
  #que.append((sx,sy))
  #d[sx][sy] = 0
  
  while que:
    lead_h,lead_w = que.popleft()
    lead = d[lead_h][lead_w]
    #lead == queの先頭にある要素を取り出す
    for i in range(4):
      nx = lead_w + dx[i]
      ny = lead_h + dy[i]
      if ny<0 or h<=ny or nx<0 or w<=nx:
        continue
      if d[nx][ny]==float("inf"):
        d[nx][ny] = lead + 1
        que.append((nx,ny))
  return lead

h, w = map(int, input().split())
maze = [list(input()) for i in range(h)]

d = [[float("inf")] * w for i in range(h)] 

que = deque([])
for i in range(h):
  for j in range(w):
    if maze[i][j] == "#":
      que.append((i,j))
      d[i][j] = 0

print(bfs())

Fixed submission:
from collections import deque

H, W = map(int, input().split())
grid = [input() for i in range(H)]

# 初期の黒('#')の位置からの距離
dist = [[-1]*W for _ in range(H)]

# '#'の位置をキューに追加（＝今回はこれが複数あるので、複数スタートとなる）
black_cells = deque()
for h in range(H):
    for w in range(W):
        if grid[h][w] == '#':
            black_cells.append((h, w))
            dist[h][w] = 0

def bfs(black_cells, dist):
    d = 0
    while black_cells:
        # キューとして使うのでpop()ではなくpopleft()
        h, w = black_cells.popleft()
        d = dist[h][w]
        for dy, dx in ((1, 0), (0, 1), (-1, 0), (0, -1)):
            new_h = h + dy
            new_w = w + dx
            if new_h < 0 or H <= new_h or new_w < 0 or W <= new_w:
                continue
            if dist[new_h][new_w] == -1:  # セルが白('.')であるのと同義
                dist[new_h][new_w] = d+1
                black_cells.append((new_h, new_w))
    return d

d = bfs(black_cells, dist)
print(d)