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23_Print-Reversed-Linked-List.py
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23_Print-Reversed-Linked-List.py
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#!/usr/bin/python
# coding=utf-8
'''
__author__ = 'sunp'
__date__ = '2019/2/17'
Given a linked list, write a function that prints the nodes of the list in reverse order.
printReversedList(1 -> 2 -> 3)
3
2
1
'''
from copy import deepcopy
class LinkNode(object):
def __init__(self, val, next=None):
self.val = val
self.next = next
def print_rl1(head):
# auxiliary stack
stack = []
while head:
stack.append(head.val)
head = head.next
while stack:
print(stack.pop())
def print_rl2(head):
# iterative
new_head = None
while head:
tmp = head.next
head.next = new_head
new_head = head
head = tmp
while new_head:
print(new_head.val)
new_head = new_head.next
def print_rl3(head):
# recursive
if not head:
return
print_rl3(head.next)
print(head.val)
if __name__ == '__main__':
test = LinkNode(1)
test.next = LinkNode(2)
test.next.next = LinkNode(3)
for print_func in [print_rl1, print_rl2, print_rl3]:
dup = deepcopy(test)
print('Output of {}:'.format(print_func.__name__))
print_func(dup)