도전: 가장자리 돌의 활로

EMPTY, BLACK, WHITE = 0, 1, 2
SIZE = 5

def neighbors(r, c):
    result = []
    for dr, dc in [(-1, 0), (1, 0), (0, -1), (0, 1)]:
        nr, nc = r + dr, c + dc
        if 0 <= nr < SIZE and 0 <= nc < SIZE:
            result.append((nr, nc))
    return result

def liberties(board, r, c):
    if board[r][c] == EMPTY:
        return 0
    count = 0
    for nr, nc in neighbors(r, c):
        if board[nr][nc] == EMPTY:
            count += 1
    return count

board = [[EMPTY] * SIZE for _ in range(SIZE)]
board[0][2] = BLACK
board[2][0] = WHITE
board[4][4] = BLACK
board[1][1] = BLACK

# 정답
print(f"상변(0,2) 활로: {liberties(board, 0, 2)}")    # 3
print(f"좌변(2,0) 활로: {liberties(board, 2, 0)}")    # 3
print(f"우하(4,4) 활로: {liberties(board, 4, 4)}")    # 2
print(f"안쪽(1,1) 활로: {liberties(board, 1, 1)}")    # 4