Python-сообщество

 def shape_len(matr, x, y):
    len = 0
    m = len(matr[0])
    x, ay, by = x - 1, y - 1, y + 1
    while x >= 0 and ay >= 0 and by < m and matr[x][ay] == '*' and matr[x][by] == '*':
        len += 1
        x -= 1
        ay -= 1
        by += 1
    return len

 def solve():
    n, m, k = [int(x) for x in input().split()]
    lst = []
    for _ in range(n):
        lst.append([e for e in input()])
    result = [['.' for _ in range(m)] for _ in range(n)]
    
    for i in range(k, n):
        for j in range(k, m):
            if lst[i][j] == '*':
                sz = shape_len(lst, i, j)
                if sz >= k:
                    result = print_shape(result, i, j, sz)
                    
    if lst != result:
        print('NO')
    else:
        print('YES')