Question

我被要求编写一个模拟MU游戏的程序：postcss-import

假设有符号M，I和U可以组合以产生符号串。 MU难题要求一个人从“公理”字符串MI开始并将其转换为字符串MU，在每个步骤中使用以下转换规则之一：

Nr.   Formal rule   Informal explanation                           Example
---   -----------   --------------------------------------------   --------------
1.    xI → xIU      Add a U to the end of any string ending in I   MI to MIU
2.    Mx → Mxx      Double the string after the M                  MIU to MIUIU
3.    xIIIy → xUy   Replace any III with a U                       MUIIIU to MUUU
4.    xUUy → xy     Remove any UU                                  MUUU to MU

这是我到目前为止所做的：

string = input("Enter a combination of M, U and I: ")

while True:
    if string and all(c in "MIU" for c in string):
        print("This is correct")
        break
        continue
    else:
        print("This is incorrect")
        break

rule = input("Enter a rule 1-4 or q to quit: ")

rule1 = (string+'U')

while True:
    if rule == ('1') and string.endswith('I'):
    print(rule1)
    break
    continue
elif rule == ('2') and string.startswith('M'):

但是，我坚持第二条规则。我假设它要求我从字符串的范围内的起点1打印字符串，因为M将是0，然后将它们一起添加以形成新的字符串？我不完全确定如何做到这一点。

Answer 1

实施规则2的方法之一可能是：

if string1.startswith(('M')):
    sub=string1[1:]
    rule2=('M'+sub+sub)
    print rule2

Answer 2

怎么样？我尝试使用python内置方法来操纵string 由于我使用的是Windows和Python 2.7，因此我必须将input转换为raw_input

同时避免使用python reserved words作为string作为variables。这可能会导致python在variables和literals

之间混淆的问题

演示代码：

# -*- coding: utf-8 -*-
myStr = raw_input("Enter a combination of M, U and I: ")

while True:
    if myStr and all(ch in "MIU" for ch in myStr):
        print("This is correct")        
        break
    else:
        print("This is incorrect")
        break

rule = raw_input("Enter a rule 1-4 or q to quit: ")

#Rule 1
# xI→xIU ; Add a U to the end of any string ending in I; e.g.   MI to MIU   
if rule == '1' and myStr.endswith('I'):        
    newStr = "".join((myStr,'U'))
    print newStr

#Rule 2
# Mx → Mxx ; Double the string after the M  ;MIU to MIUIU
elif rule == '2' and myStr.startswith('M') and not myStr.endswith('I'):
    newStr = "".join((myStr,myStr[1:]))
    print newStr

<强>输出：

Python 2.7.9 (default, Dec 10 2014, 12:24:55) [MSC v.1500 32 bit (Intel)] on win32
Type "copyright", "credits" or "license()" for more information.
>>> ================================ RESTART ================================
>>> 
Enter a combination of M, U and I: MI
This is correct
Enter a rule 1-4 or q to quit: 1
MIU
>>> ================================ RESTART ================================
>>> 
Enter a combination of M, U and I: MU
This is correct
Enter a rule 1-4 or q to quit: 2
MUU
>>>
>>> 
Enter a combination of M, U and I: MIU
This is correct
Enter a rule 1-4 or q to quit: 2
MIUIU
>>>

在python中将字符附加到字符串

2 个答案: