python字典序问题实例

本文实例讲述了python字典序问题，分享给大家供大家参考。具体如下：

问题描述:

将字母从左向右的次序与字母表中的次序相同,且每个字符最大出现一次..例如:a,b,ab,bc,xyz等都是升序的字符串.现对字母表A产生的所有长度不超过6的升序字符串按照字典充排列并编码如下:

1 2 .. 26 27 28 ...

a b .. z ab ac ..

对一个升序字符串,迅速计算出它在上述字典中的编码。

实现代码如下:

    import string
    all_letter = string.ascii_lowercase
    def gen_dict():
      result = {}
      list_num_one = [ a_letter for a_letter in all_letter ]
      list_num_two = [ i + j for i in all_letter for j in all_letter[all_letter.find(i)+1:]]
      list_num_three = [ i + j + k for i in all_letter 
               for j in all_letter[all_letter.find(i)+1:]
               for k in all_letter[all_letter.find(j)+1:]]
      list_num_four = [ i + j + k + l for i in all_letter 
               for j in all_letter[all_letter.find(i)+1:]
               for k in all_letter[all_letter.find(j)+1:]
               for l in all_letter[all_letter.find(k)+1:]]
      list_num_five = [ i + j + k + l + m for i in all_letter 
               for j in all_letter[all_letter.find(i)+1:]
               for k in all_letter[all_letter.find(j)+1:]
               for l in all_letter[all_letter.find(k)+1:]
               for m in all_letter[all_letter.find(l)+1:]]
      list_num_six = [ i + j + k + l + m + n  for i in all_letter
          for j in all_letter[all_letter.find(i)+1:]
          for k in all_letter[all_letter.find(j)+1:]
          for l in all_letter[all_letter.find(k)+1:]
          for m in all_letter[all_letter.find(l)+1:]
          for n in all_letter[all_letter.find(m)+1:]
          ]
      for key,value in enumerate(list_num_one + list_num_two + list_num_three + list_num_four + list_num_five + list_num_six):
        result.setdefault(key+1,value)
      return result

    my_dict = gen_dict()
    value_to_get = 'abcdef'
    for key,value in my_dict.iteritems():
      if value == value_to_get:
        print key

结果:83682　　

即abcdef在字典中的编码。

希望本文所述对大家的Python程序设计有所帮助。