Problem p03053 (python)

Fixed submission:
H,W = list(map(int,input().split()))
A = [list(str(input())) for i in range(H)]
 
black = []
 
cnt = 0
 
for i in range(H):
    for j in range(W):
        if A[i][j] == "#":
            black.append([i,j])
 
length = len(black)
            
while (length < H*W):
    gray = []
    for l in black:
        if l[1] != 0:
            c1 = (l[0],l[1]-1)
            if A[c1[0]][c1[1]] == ".":
                gray.append(c1)
                A[c1[0]][c1[1]] = "#"
        if l[1] != W-1:
            c2 = (l[0],l[1]+1)
            if  A[c2[0]][c2[1]] == ".":
                gray.append(c2)
                A[c2[0]][c2[1]] = "#"
        if l[0] != 0:
            c3 = (l[0]-1,l[1])
            if  A[c3[0]][c3[1]] == ".":
                gray.append(c3)
                A[c3[0]][c3[1]] = "#"
        if l[0] != H-1:
            c4 = (l[0]+1,l[1])
            if  A[c4[0]][c4[1]] == ".":
                gray.append(c4)
                A[c4[0]][c4[1]] = "#"
    
    gray = list(set(gray))
    black = [l for l in gray]
    
    cnt += 1
    length += len(black)
    
print(cnt)

Buggy submission (verdict: Runtime Error):
def pixel_input(H,W,border="."):
    pixel = [[border]*(W+2)] + \
    [[border] + list(input()) + [border] for _ in range(H)] + \
    [[border]*(W+2)]
    return pixel
  
H,W=map(int,input().split())
A=pixel_input(H,W)

cnt=0
q,r=[],[]
for i in range(1,H+1):
    for j in range(1,W+1):
        if A[i][j]=="#":
            q.append((i,j))
if len(q)==H*W:
    print(0)
    sys.exit()
while(q):
    while(q):
        i,j=q.pop()
        if A[i-1][j]==".":
            if i-1!=0:
                A[i-1][j]="#"
                r.append((i-1,j))
        if A[i+1][j]==".":
            if i+1!=H+1:
                A[i+1][j]="#"
                r.append((i+1,j))
        if A[i][j-1]==".":
            if j-1!=0:
                A[i][j-1]="#"
                r.append((i,j-1))
        if A[i][j+1]==".":
            if j+1!=W+1:
                A[i][j+1]="#"
                r.append((i,j+1))
    q=[i for i in r]
    r=[]
    cnt+=1
print(cnt-1)

Buggy submission (verdict: Runtime Error):
def pixel_input(H,W,border="."):
    pixel = [[border]*(W+2)] + \
    [[border] + list(input()) + [border] for _ in range(H)] + \
    [[border]*(W+2)]
    return pixel
  
H,W=map(int,input().split())
A=pixel_input(H,W)

cnt=0
q,r=[],[]
for i in range(1,H+1):
    for j in range(1,W+1):
        if A[i][j]=="#":
            q.append((i,j))
if len(q)==H*W:
    print(0)
    sys.exit()
while(q):
    while(q):
        i,j=q.pop()
        if A[i-1][j]==".":
            if i-1!=0:
                A[i-1][j]="#"
                r.append((i-1,j))
        if A[i+1][j]==".":
            if i+1!=H+1:
                A[i+1][j]="#"
                r.append((i+1,j))
        if A[i][j-1]==".":
            if j-1!=0:
                A[i][j-1]="#"
                r.append((i,j-1))
        if A[i][j+1]==".":
            if j+1!=W+1:
                A[i][j+1]="#"
                r.append((i,j+1))
    q=[i for i in r]
    r=[]
    cnt+=1
print(cnt-1)

Buggy submission (verdict: Runtime Error):
H,W = list(map(int,input().split()))

A = [list(str(input())) for i in range(H)]

white = []
black = []

length = sum([a.count(".") for a in A])
cnt = 0

while (length > 0):
    gray = []
    for i in range(W):
        for j in range(H):
            if A[i][j] == "#":
                black.append([i,j])
            else:
                white.append([i,j])
       
    for l in white:
        if [l[0],l[1]-1] in black or [l[0],l[1]+1] in black or [l[0]-1,l[1]] in black or [l[0]+1,l[1]] in black:
            gray.append(l)

    for l in gray:
        black.append(l)
        white.remove(l)
        
    cnt += 1
    length = len(white)
    
print(cnt)