增加字母表

Question

我正在为面试而练习，过去问面试者的一个问题是--“写一个程序来增加字母表，使A变成B，Z变成AA，ABZ变成ACA。”

我需要帮助，了解我如何才能达到预期的结果。我尝试使用一个简单的函数，它增加了Ascii值，当然可以使用if循环获得结果，chracter "z“作为特例。

def give_string(random_string):
    word = ""
    
    for i in range(len(random_string)):
        if(random_string[i] == 'z' or random_string[i] == 'Z'):
            #if "z or Z" is at the begining of the string
            if(random_string[0] == 'z' or 'Z' and i == 0):
                if(i == 'z'):
                    word = word + 'aa'
                else:
                    word = word + 'AA'
                
                if(len(random_string) == 1):
                    return word

            # if the last character is "z or Z", we also need to change the first character to a or A
            # i.e., BCZ = ADA not CDAA
            elif(random_string[-1] == 'z' or 'Z' and i == (len(random_string) - 1)):
                if(random_string[-1] == 'z'):
                    word = word + 'a'
                    word = word[:0] + 'a' + word[0+1:]
                else:
                    word = word + 'A'
                    word = word[:0] + 'A' + word[0+1:]
                   
                return word

            #if "z or Z" is somewhere in the middle of the string
            else:           
                print("going to the middle")
                if(random_string[i] == 'z'):    
                    word = word + 'aa'
                else:
                    word = word + 'AA'

        #if it is any character other than "z or Z"            
        else:  
            word = word + chr(ord(random_string[i])+1)
    
    return word


if __name__ == '__main__':
    my_string = "ZbgsGD"

    print(my_string)
    print(give_string(my_string))

但是，我想知道的是，还有什么办法可以解决我错过的这个问题，

如您所见，代码确实完成了获得正确结果的工作。我只想知道是否还有其他更简单的方法来达到我所缺少的预期结果，因为使用所有这些循环似乎不是最好的方法。

Answer 1

显示类似于Potential interview question: building a pseudocode string incrementer similar to Excel columns

本质上，它要求构建一个字符串增量器，以便A+1=B.Z+1= AA，AA +1=AB.ZZ +1=AAA以此类推。

码

def incr(s):
    '''
        Incremental for string s
        
    '''
    def incr_chr(c):
        '''
            Helper function that provides single character incrementer
        
           carry and next character for character incrment
        '''
        if c in ('z', 'Z'):
            return 1, 'a' if c.islower() else 'A'          # with carry one
        else:
            return 0, chr(ord(c) + 1) # with carry zero
        

    lst = list(s)                            # string to list since string immutable
    result = []
    while lst:
        carry, next_ = incr_chr(lst.pop())   # increment last letter in list
        result.append(next_)                 # add last incremented character to result

        if not carry:                        # break if no carry
            break
        if not lst:
            result.append('a' if next_.islower() else 'A')  # empty lst but remaining carry
            
    result += lst[::-1]                      # add remainder of string list to result
    
    return ''.join(result[::-1])             # list to string in reverse order

测试

for t in  ['a', 'A', 'b', 'z', 'Z', 'ABZ', 'abz', 'abcdz', 'ZbgsGD', 'zzz', 'ZZ']:
    print(f'{t} -> {incr(t)}')

输出

a -> b
A -> B
b -> c
z -> aa
Z -> AA
ABZ -> ACA
abz -> aca
abcdz -> abcea
ZbgsGD -> ZbgsGE
zzz -> aaaa
ZZ -> AAA
​