Buggy python submission (verdict: Time Limit Exceeded):
import sys
import heapq

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

def removeWalls(wallPointH,wallPointW):
  if maze[wallPointH][wallPointW]=="#":
    changeTo = "."
  elif maze[wallPointH][wallPointW]=="1":
    changeTo = "0"
  if maze[wallPointH][wallPointW]=="#" or maze[wallPointH][wallPointW]=="1":
    maze[wallPointH][wallPointW]=changeTo
    if wallPointH+1 <= H-1:
      removeWalls(wallPointH+1,wallPointW)
    if wallPointW+1 <= W-1:
      removeWalls(wallPointH,wallPointW+1)

if maze[0][0]=="#":
  flag=1
else:
  flag=0
      
que = [[flag,0,0]]
heapq.heapify(que)
count = 0
      
while que:
  qu = heapq.heappop(que)
  if qu[0]==1:
    heapq.heappush(que, qu)
    count += 1
    for q in que:#いったん"#"の撤去作業を行う
      q[0]=0
      removeWalls(q[1],q[2])
  else:#queの中身にまだ進める場所があるなら
    nowH = qu[1]
    nowW = qu[2]
    if nowH==H-1 and nowW==W-1:#ゴールの場合
      print(count)
      sys.exit()
    else:#それ以外の場合
      #右近傍と下近傍、それぞれマップの中ならqueに格納。
      if nowH+1 <= H-1:
        if maze[nowH+1][nowW]=="#":
          maze[nowH+1][nowW]=="1"
          heapq.heappush(que, [1,nowH+1,nowW])
        elif maze[nowH+1][nowW]==".":
          maze[nowH+1][nowW]=="0"
          heapq.heappush(que, [0,nowH+1,nowW])
      if nowW+1 <= W-1:
        if maze[nowH][nowW+1]=="#":
          maze[nowH][nowW+1]=="1"
          heapq.heappush(que, [1,nowH,nowW+1])
        elif maze[nowH][nowW+1]==".":
          maze[nowH][nowW+1]=="0"
          heapq.heappush(que, [0,nowH,nowW+1])
        



Fixed submission:
import sys
import heapq

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

def removeWalls(wallPointH,wallPointW):
  if maze[wallPointH][wallPointW]=="#":
    changeTo = "."
  elif maze[wallPointH][wallPointW]=="1":
    changeTo = "0"
  if maze[wallPointH][wallPointW]=="#" or maze[wallPointH][wallPointW]=="1":
    maze[wallPointH][wallPointW]=changeTo
    if wallPointH+1 <= H-1:
      removeWalls(wallPointH+1,wallPointW)
    if wallPointW+1 <= W-1:
      removeWalls(wallPointH,wallPointW+1)

if maze[0][0]=="#":
  flag=1
else:
  flag=0
      
que = [[flag,0,0]]
heapq.heapify(que)
count = 0
      
while que:
  qu = heapq.heappop(que)
  if qu[0]==1:
    heapq.heappush(que, qu)
    count += 1
    for q in que:#いったん"#"の撤去作業を行う
      q[0]=0
      removeWalls(q[1],q[2])
  else:#queの中身にまだ進める場所があるなら
    nowH = qu[1]
    nowW = qu[2]
    if nowH==H-1 and nowW==W-1:#ゴールの場合
      print(count)
      sys.exit()
    else:#それ以外の場合
      #右近傍と下近傍、それぞれマップの中ならqueに格納。
      if nowH+1 <= H-1:
        if maze[nowH+1][nowW]=="#":
          maze[nowH+1][nowW]="1"
          heapq.heappush(que, [1,nowH+1,nowW])
        elif maze[nowH+1][nowW]==".":
          maze[nowH+1][nowW]="0"
          heapq.heappush(que, [0,nowH+1,nowW])
      if nowW+1 <= W-1:
        if maze[nowH][nowW+1]=="#":
          maze[nowH][nowW+1]="1"
          heapq.heappush(que, [1,nowH,nowW+1])
        elif maze[nowH][nowW+1]==".":
          maze[nowH][nowW+1]="0"
          heapq.heappush(que, [0,nowH,nowW+1])

Buggy python submission (verdict: Time Limit Exceeded):
import sys
import heapq

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

def removeWalls(wallPointH,wallPointW):
  if maze[wallPointH][wallPointW]=="#":
    maze[wallPointH][wallPointW]="."
    if wallPointH+1 <= H-1:
      removeWalls(wallPointH+1,wallPointW)
    if wallPointW+1 <= W-1:
      removeWalls(wallPointH,wallPointW+1)

que = [[0,0,0]]
heapq.heapify(que)
count = 0
      
while que:
  qu = heapq.heappop(que)
  #print(que)
  if qu[0]==1:
    heapq.heappush(que, qu)
    count += 1
    for q in que:#いったん"#"の撤去作業を行う
      q[0]=0
      removeWalls(q[1],q[2])
  else:#queの中身にまだTrueがあるなら
    now = qu
    nowH = now[1]
    nowW = now[2]
    if maze[nowH][nowW]=="#":#行き止まりの場合
      heapq.heappush(que, [1,nowH,nowW])
      continue
    elif nowH==H-1 and nowW==W-1:#ゴールの場合
      print(count)
      sys.exit()
    else:#それ以外の場合
      #右近傍と下近傍、それぞれマップの中ならqueに格納。
      if nowH+1 <= H-1:
        heapq.heappush(que, [0,nowH+1,nowW])
      if nowW+1 <= W-1:
        heapq.heappush(que, [0,nowH,nowW+1])
        



Fixed submission:
import sys
import heapq

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

def removeWalls(wallPointH,wallPointW):
  if maze[wallPointH][wallPointW]=="#":
    changeTo = "."
  elif maze[wallPointH][wallPointW]=="1":
    changeTo = "0"
  if maze[wallPointH][wallPointW]=="#" or maze[wallPointH][wallPointW]=="1":
    maze[wallPointH][wallPointW]=changeTo
    if wallPointH+1 <= H-1:
      removeWalls(wallPointH+1,wallPointW)
    if wallPointW+1 <= W-1:
      removeWalls(wallPointH,wallPointW+1)

if maze[0][0]=="#":
  flag=1
else:
  flag=0
      
que = [[flag,0,0]]
heapq.heapify(que)
count = 0
      
while que:
  qu = heapq.heappop(que)
  if qu[0]==1:
    heapq.heappush(que, qu)
    count += 1
    for q in que:#いったん"#"の撤去作業を行う
      q[0]=0
      removeWalls(q[1],q[2])
  else:#queの中身にまだ進める場所があるなら
    nowH = qu[1]
    nowW = qu[2]
    if nowH==H-1 and nowW==W-1:#ゴールの場合
      print(count)
      sys.exit()
    else:#それ以外の場合
      #右近傍と下近傍、それぞれマップの中ならqueに格納。
      if nowH+1 <= H-1:
        if maze[nowH+1][nowW]=="#":
          maze[nowH+1][nowW]="1"
          heapq.heappush(que, [1,nowH+1,nowW])
        elif maze[nowH+1][nowW]==".":
          maze[nowH+1][nowW]="0"
          heapq.heappush(que, [0,nowH+1,nowW])
      if nowW+1 <= W-1:
        if maze[nowH][nowW+1]=="#":
          maze[nowH][nowW+1]="1"
          heapq.heappush(que, [1,nowH,nowW+1])
        elif maze[nowH][nowW+1]==".":
          maze[nowH][nowW+1]="0"
          heapq.heappush(que, [0,nowH,nowW+1])

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

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

def removeWalls(wallPointH,wallPointW):
  if maze[wallPointH][wallPointW]=="#":
    maze[wallPointH][wallPointW]="."
    if wallPointH+1 <= H-1:
      removeWalls(wallPointH+1,wallPointW)
    if wallPointW+1 <= W-1:
      removeWalls(wallPointH,wallPointW+1)

que = [[0,0,0]]
count = 0
      
while que:
  #print(que)
  if que[0][0]==1:
    que.sort()
  if que[0][0]==1:
    count += 1
    for q in que:#いったん"#"の撤去作業を行う
      q[0]=0
      removeWalls(q[1],q[2])
  else:#queの中身にまだTrueがあるなら
    now = que.pop(0)
    nowH = now[1]
    nowW = now[2]
    if maze[nowH][nowW]=="#":#行き止まりの場合
      que.append([1,nowH,nowW])
      continue
    elif nowH==H-1 and nowW==W-1:#ゴールの場合
      print(count)
      sys.exit()
    else:#それ以外の場合
      #右近傍と下近傍、それぞれマップの中ならqueに格納。
      if nowH+1 <= H-1:
        que.append([0,nowH+1,nowW])
      if nowW+1 <= W-1:
        que.append([0,nowH,nowW+1])



Fixed submission:
import sys
import heapq

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

def removeWalls(wallPointH,wallPointW):
  if maze[wallPointH][wallPointW]=="#":
    changeTo = "."
  elif maze[wallPointH][wallPointW]=="1":
    changeTo = "0"
  if maze[wallPointH][wallPointW]=="#" or maze[wallPointH][wallPointW]=="1":
    maze[wallPointH][wallPointW]=changeTo
    if wallPointH+1 <= H-1:
      removeWalls(wallPointH+1,wallPointW)
    if wallPointW+1 <= W-1:
      removeWalls(wallPointH,wallPointW+1)

if maze[0][0]=="#":
  flag=1
else:
  flag=0
      
que = [[flag,0,0]]
heapq.heapify(que)
count = 0
      
while que:
  qu = heapq.heappop(que)
  if qu[0]==1:
    heapq.heappush(que, qu)
    count += 1
    for q in que:#いったん"#"の撤去作業を行う
      q[0]=0
      removeWalls(q[1],q[2])
  else:#queの中身にまだ進める場所があるなら
    nowH = qu[1]
    nowW = qu[2]
    if nowH==H-1 and nowW==W-1:#ゴールの場合
      print(count)
      sys.exit()
    else:#それ以外の場合
      #右近傍と下近傍、それぞれマップの中ならqueに格納。
      if nowH+1 <= H-1:
        if maze[nowH+1][nowW]=="#":
          maze[nowH+1][nowW]="1"
          heapq.heappush(que, [1,nowH+1,nowW])
        elif maze[nowH+1][nowW]==".":
          maze[nowH+1][nowW]="0"
          heapq.heappush(que, [0,nowH+1,nowW])
      if nowW+1 <= W-1:
        if maze[nowH][nowW+1]=="#":
          maze[nowH][nowW+1]="1"
          heapq.heappush(que, [1,nowH,nowW+1])
        elif maze[nowH][nowW+1]==".":
          maze[nowH][nowW+1]="0"
          heapq.heappush(que, [0,nowH,nowW+1])

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

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

"""
①BFSでゴールまで行けるかを試す
↓行けない
＃の位置を覚えておく（次に探索すべきqueに格納＆1つ目の数字として、1を入れておく。
↓
queの中身が全部行き止まりリストになったら（ソートして判断）、いったんループをやめて、count += 1
行き止まりリストの座標含む近傍の＃を全部.に変える。
↓
queの中身の各リストの1つ目の数字をすべて0に帰る。
↓
①に戻る
"""

def removeWalls(wallPointH,wallPointW):
  if maze[wallPointH][wallPointW]=="#":
    maze[wallPointH][wallPointW]="."
    if wallPointH+1 <= H-1:
      removeWalls(wallPointH+1,wallPointW)
    if wallPointW+1 <= W-1:
      removeWalls(wallPointH,wallPointW+1)

que = [[0,0,0]]
count = 0
      
while que:
  #print(que)
  if que[0][0]==1:
    que.sort()
  if que[0][0]==1:
    count += 1
    for q in que:#いったん"#"の撤去作業を行う
      q[0]=0
      removeWalls(q[1],q[2])
  else:#queの中身にまだTrueがあるなら
    now = que.pop(0)
    nowH = now[1]
    nowW = now[2]
    if maze[nowH][nowW]=="#":#行き止まりの場合
      que.append([1,nowH,nowW])
      continue
    elif nowH==H-1 and nowW==W-1:#ゴールの場合
      print(count)
      sys.exit()
    else:#それ以外の場合
      #右近傍と下近傍、それぞれマップの中ならqueに格納。
      if nowH+1 <= H-1:
        que.append([0,nowH+1,nowW])
      if nowW+1 <= W-1:
        que.append([0,nowH,nowW+1])



Fixed submission:
import sys
import heapq

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

def removeWalls(wallPointH,wallPointW):
  if maze[wallPointH][wallPointW]=="#":
    changeTo = "."
  elif maze[wallPointH][wallPointW]=="1":
    changeTo = "0"
  if maze[wallPointH][wallPointW]=="#" or maze[wallPointH][wallPointW]=="1":
    maze[wallPointH][wallPointW]=changeTo
    if wallPointH+1 <= H-1:
      removeWalls(wallPointH+1,wallPointW)
    if wallPointW+1 <= W-1:
      removeWalls(wallPointH,wallPointW+1)

if maze[0][0]=="#":
  flag=1
else:
  flag=0
      
que = [[flag,0,0]]
heapq.heapify(que)
count = 0
      
while que:
  qu = heapq.heappop(que)
  if qu[0]==1:
    heapq.heappush(que, qu)
    count += 1
    for q in que:#いったん"#"の撤去作業を行う
      q[0]=0
      removeWalls(q[1],q[2])
  else:#queの中身にまだ進める場所があるなら
    nowH = qu[1]
    nowW = qu[2]
    if nowH==H-1 and nowW==W-1:#ゴールの場合
      print(count)
      sys.exit()
    else:#それ以外の場合
      #右近傍と下近傍、それぞれマップの中ならqueに格納。
      if nowH+1 <= H-1:
        if maze[nowH+1][nowW]=="#":
          maze[nowH+1][nowW]="1"
          heapq.heappush(que, [1,nowH+1,nowW])
        elif maze[nowH+1][nowW]==".":
          maze[nowH+1][nowW]="0"
          heapq.heappush(que, [0,nowH+1,nowW])
      if nowW+1 <= W-1:
        if maze[nowH][nowW+1]=="#":
          maze[nowH][nowW+1]="1"
          heapq.heappush(que, [1,nowH,nowW+1])
        elif maze[nowH][nowW+1]==".":
          maze[nowH][nowW+1]="0"
          heapq.heappush(que, [0,nowH,nowW+1])