import random

print("=====拿棋子游戏【加强AI版】=====")
print("规则：一共21颗棋子，每次拿1~3颗，拿到最后一颗获胜")
total = 21

while True:
print(f"\n剩余棋子：{total}")
# 玩家回合
while True:
try:
player = int(input("请拿棋子(1‑3)："))
if 1 <= player <= 3 and player <= total:
break
else:
print("只能拿1‑3颗，不能超过剩余棋子！")
except ValueError:
print("请输入数字！")

total -= player
if total <= 0:
print("🎉恭喜，你拿到最后一颗，你赢了！")
break

# AI：优先抢占4的倍数制胜点
want = total % 4
if want == 0:
take = random.randint(1, min(3, total))
else:
take = want

print(f"电脑拿走 {take} 颗")
total -= take
if total <= 0:
print("💻电脑拿到最后一颗，你输了！")
break