Reverse a Linked List In Place

EasyPython

Problem

Given the head of a singly linked list, reverse the list in place and return the new head. Do not create a second list or use extra nodes to store the result.

Formal Specification

Implement a function that takes the head node of a singly linked list and returns the head node of the reversed list. Each node has two fields: val and next.

Constraints

0 <= number of nodes <= 10^5
-10^9 <= Node.val <= 10^9
The list is singly linked
Must use O(1) extra space

Function Signature

def reverse_linked_list(head):

CodePython 3

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