逆序栈

只使用递归和栈操作实现栈的逆序

#!/usr/bin/env python
# --*-- coding: utf-8 --*--

def popbottom(s):
    x = s.pop()
    if not s:
        return x
    else:
        bottom = popbottom(s)
        s.append(x)
        return bottom

def reverse(s):
    if not s:
        return
    x = popbottom(s)
    if not s:
        s.append(x)
    else:
        reverse(s)
        s.append(x)

if __name__ == ‘__main__‘:
    s = [1, 2, 3, 4, 5, 6]
    print(‘逆序前:‘)
    print(s)
    reverse(s)
    print(‘逆序后:‘)
    print(s)