python代码 程序员编程艺术 1.1

   1:  def simpleShift(str, n):

   2:      tmpStr = str[n:] + str[:n]

   3:      return tmpStr

   4:   

   5:  def LeftShiftOne(str):

   6:      char = str[0]

   7:   

   8:      tmpStr = ‘‘

   9:      for i in range(1, len(str)):

  10:          tmpStr += str[i]

  11:      tmpStr += char

  12:   

  13:      return tmpStr

  14:   

  15:  def LeftRotateString(str, n):

  16:      for i in range(n):

  17:          str = LeftShiftOne(str)

  18:      return str

  19:   

  20:  def ReverseString(str):

  21:      l = len(str)

  22:      for i in range(l/2):

  23:          char = str[i]

  24:          # reversed + right + to be reversed + left + reversed

  25:          str = str[:i ] + str[l - i - 1] + str[i + 1: l - i - 1] + char + str[l - i:]

  26:      return str

  27:   

  28:  def ReverseWords(str):

  29:      words = str.split()

  30:      l = len(words)

  31:      for i in range(l/2):

  32:          word = words[i]

  33:          words[i] = words[l - i - 1]

  34:          words[l - i - 1] = word

  35:   

  36:      str = ‘‘

  37:      for word in words:

  38:          str += word + ‘ ‘

  39:      return str

  40:   

  41:  def main():

  42:      s = ‘abcdefg‘

  43:      n = 3

  44:   

  45:      print ‘1. Simple shift‘

  46:      str = simpleShift(s, n)

  47:      print str

  48:   

  49:      print ‘2. Left rotate string‘

  50:      str = LeftRotateString(s, n)

  51:      print str

  52:   

  53:      print ‘3. reverse string‘

  54:      str = ReverseString(s[:n])

  55:      str = str + ReverseString(s[n:])

  56:      str = ReverseString(str)

  57:      print str

  58:   

  59:      print ‘4. reverse words‘

  60:      s = ‘I am a student.‘

  61:      str = ReverseWords(s)

  62:      print str

  63:   

  64:  if __name__ == ‘__main__‘:

  65:      main()