https://school.programmers.co.kr/learn/courses/30/lessons/17679 모범 답안 def pop_num(b, m, n): pop_set = set() # search for i in range(1, n): for j in range(1, m): if b[i][j] == b[i - 1][j - 1] == b[i - 1][j] == b[i][j - 1] != '_': pop_set |= set([(i, j), (i - 1, j - 1), (i - 1, j), (i, j - 1)]) # set_board for i, j in pop_set: b[i][j] = 0 for i, row in enumerate(b): empty = ['_'] * row.count(0) b[..