DataStructure/Linked List

Reverse Linked List

ND Paul Kim 2018. 10. 26. 15:16

Reverse a singly linked list.

Example:

Input: 1->2->3->4->5->NULL
Output: 5->4->3->2->1->NULL

Follow up:

A linked list can be reversed either iteratively or recursively. Could you implement both?


My Solution:

# Definition for singly-linked list.
# class ListNode:
# def __init__(self, x):
# self.val = x
# self.next = None

class Solution:
def reverseList(self, head):
"""
:type head: ListNode
:rtype: ListNode
"""
current = head
prev = None

while current:
next_node = current.next
current.next = prev
prev = current
current = next_node

return prev