1 import random
 2 while True:
 3     x=eval(put("请输入模拟次数:"))
 4     change = 0
 5     Nchange = 0
 6 
 7     for i in range (1,x):
 8         a = random.randrange(1,4)     ##车所在门
 9         b = random.randrange(1,4)     ##选的门
10 
11         if a==b:
12             Nchange = Nchange + 1
13         elif a!=b:
14             change = change + 1
15     print("更改后选中汽车的概率为",change/x)
16 
17     print("不改选中汽车的概率为",Nchange/x)