Last updated on March 9th, 2025 at 12:10 am

Here, we see a Reverse Linked List LeetCode Solution. This Leetcode problem is solved using different approaches in many programming languages, such as C++, Java, JavaScript, Python, etc.

List of all LeetCode Solution

Topics

Linked List

Companies

Adobe, Amazon, Apple, Bloomberg, Facebook, Microsoft, Snapchat, Twitter, Uber, Yahoo, Yelp, Zenefits

Level of Question

Easy

Reverse Linked List LeetCode Solution

1. Problem Statement

Given the head of a singly linked list, reverse the list, and return the reversed list.

Example 1: (fig-1)
Input: head = [1,2,3,4,5]
Output: [5,4,3,2,1]

Example 2: (fig-2)
Input: head = [1,2]
Output: [2,1]

Example 3:
Input: head = []
Output: []

2. Coding Pattern Used in Solution

The coding pattern used in all the provided implementations is “In-place Reversal of a LinkedList”. This pattern is commonly used when reversing a linked list or performing operations that require modifying the structure of the linked list without using extra space.

3. Code Implementation in Different Languages

3.1 Reverse Linked List C++

class Solution {
public:
    ListNode* reverseList(ListNode* head) {
        ListNode *pre = new ListNode(0), *cur = head;
        pre -> next = head;
        while (cur && cur -> next) {
            ListNode* temp = pre -> next;
            pre -> next = cur -> next;
            cur -> next = cur -> next -> next;
            pre -> next -> next = temp;
        }
        return pre -> next;
    }
};

3.2 Reverse Linked List Java

class Solution {
    public ListNode reverseList(ListNode head) {
        if(head==null || head.next==null)
            return head;
        ListNode nextNode=head.next;
        ListNode newHead=reverseList(nextNode);
        nextNode.next=head;
        head.next=null;
        return newHead;
    }
}

3.3 Reverse Linked List JavaScript

var reverseList = function(head) {
    let [prev, current] = [null, head]
    while(current) {
        [current.next, prev, current] = [prev, current, current.next]
    }
    return prev
};

3.4 Reverse Linked List Python

class Solution(object):
    def reverseList(self, head):
        prev = None
        curr = head

        while curr:
            next = curr.next
            curr.next = prev
            prev = curr
            curr = next
        return prev

4. Time and Space Complexity

	Time Complexity	Space Complexity
C++	O(n)	O(1)
Java	O(n)	O(n)
JavaScript	O(n)	O(1)
Python	O(n)	O(1)