Reversed Linked List
Problem Statement
Given the head of a singly linked list, reverse the list, and return the reversed list.
Example 1
Input: head = [1,2,3,4,5]
Output: [5,4,3,2,1]
Example 2
Input: head = [1,2]
Output: [2,1]
Example 1
Input: head = []
Output: []
Constraints:
- The number of nodes in the list is the range [0, 5000].
- -5000 <= Node.val <= 5000
Code
Python Code
# 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
"""
if not head or not head.next:
return head
second = head.next
reverse = self.reverseList(second)
second.next = head
head.next = None
return reverse