栈和队列数据结构的基本概念及其相关的Python实现

#!/usr/bin/env python 
 
#定义一个列表来模拟栈 
stack = [] 
 
#进栈,调用列表的append()函数加到列表的末尾,strip()没有参数是去掉首尾的空格 
def pushit(): 
  stack.append(raw_input('Enter new string: ').strip()) 
 
#出栈,用到了pop()函数 
def popit(): 
  if len(stack) == 0: 
    print 'Cannot pop from an empty stack!' 
  else: 
    print 'Removed [', stack.pop(), ']' 
 
#编历栈 
def viewstack(): 
  print stack 
 
#CMDs是字典的使用 
CMDs = {'u': pushit, 'o': popit, 'v': viewstack} 
 
#pr为提示字符 
def showmenu(): 
  pr = """ 
  p(U)sh 
  p(O)p 
  (V)iew 
  (Q)uit 
    Enter choice: """ 
 
  while True: 
    while True: 
      try: 
        #先用strip()去掉空格,再把第一个字符转换成小写的 
        choice = raw_input(pr).strip()[0].lower() 
      except (EOFError, KeyboardInterrupt, IndexError): 
        choice = 'q' 
 
      print '\nYou picked: [%s]' % choice 
      if choice not in 'uovq': 
        print 'Invalid option, try again' 
      else: 
        break 
 
#CMDs[]根据输入的choice从字典中对应相应的value,比如说输入u,从字典中得到value为pushit,执行pushit()进栈操作 
    if choice == 'q': 
      break 
    CMDs[choice]() 
 
#判断是否是从本文件进入,而不是被调用 
if __name__ == '__main__': 
  showmenu() 

#!/usr/bin/env python 
 
queue = [] 
 
def enQ(): 
  queue.append(raw_input('Enter new string: ').strip()) 
 
#调用list的列表的pop()函数.pop(0)为列表的第一个元素 
def deQ(): 
  if len(queue) == 0: 
    print 'Cannot pop from an empty queue!' 
  else: 
    print 'Removed [', queue.pop(0) ,']' 
 
def viewQ(): 
  print queue 
 
CMDs = {'e': enQ, 'd': deQ, 'v': viewQ} 
 
def showmenu(): 
  pr = """ 
  (E)nqueue 
  (D)equeue 
  (V)iew 
  (Q)uit 
    Enter choice: """ 
 
  while True: 
    while True: 
      try: 
        choice = raw_input(pr).strip()[0].lower() 
      except (EOFError, KeyboardInterrupt, IndexError): 
        choice = 'q' 
 
      print '\nYou picked: [%s]' % choice 
      if choice not in 'devq': 
        print 'Invalid option, try again' 
      else: 
        break 
    if choice == 'q': 
      break 
    CMDs[choice]() 
 
if __name__ == '__main__': 
  showmenu()