Reverse Linked List
Explore how to reverse a singly linked list using in-place manipulation techniques. Learn to efficiently update the head of the list while optimizing memory usage. This lesson helps you grasp the logic behind linked list reversal and apply a practical coding solution.
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Statement
Given the head of a singly linked list, reverse the linked list and return its updated head.
Constraints:
Let n be the number of nodes in a linked list.
-
n -
Node.value
Examples
Understand the problem
Let’s take a moment to make sure you’ve correctly understood the problem. The quiz below helps you check if you’re solving the correct problem:
What is the output if the following linked list is provided as input?
4 → 2 → 7 → 8 → 9 → 0 → 2
9 → 0 → 2 → 8 → 4 → 2 → 7
7 → 2 → 4 → 8 → 2 → 0 → 9
2 → 0 → 9 → 8 → 7 → 2 → 4
0 → 2 → 2 → 4 → 8 → 9
Figure it out!
We have a game for you to play. Rearrange the logical building blocks to develop a clearer understanding of how to solve this problem.
Try it yourself
Implement your solution in the following coding playground.
# Definition for a Linked List node# class ListNode:# def __init__(self, val=0, next=None):# self.val = val# self.next = nextfrom ds_v1.LinkedList.LinkedList import ListNodedef reverse(head):# Replace this placeholder return statement with your codereturn None