AtCoder Beginner Contest 96-C

C - Grid Repainting 2

If there is at least one square black which is arounded by white squares,

square1001 cannot achieve his objective.

So check this.
if there is a black square, count how many white squares which is sided it.

I want to think time complexity.
height is at most 50.
width is at most 50.
for-loop which is checked whether the square is black or white is 50 * 50.
if the square is black, check the square sided by black square for 4 times.
So, 50 * 50 * 4 = 10000.

My Solution

H, W = map(int,input().split())
sw_list = []
sw_list.append(["."]*(W+2))
[sw_list.append(["."] + list(input()) + ["."]) for _ in range(H)]
sw_list.append(["."]*(W+2))
def check():
    for h in range(1,H+1):
        for w in range(1,W+1):
            if sw_list[h][w] == "#":
                if all([sw_list[h-dh][w-dw]=="." for dh,dw in [(-1,0),(0,-1),(1,0),(0,1)]]):
                    return False
    return True
if check():
    print("Yes")
else:
    print("No")