Reverse Linked List Recursively in Java

Reverse Linked List Recursively in Java

This guide explains the intuition, optimized approach, and Java implementation for reverse linked list recursively in java, with practical tips for interviews and production coding standards.

Problem

Reverse a singly linked list using recursion.

Example

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

Approach

Recursively reverse the sublist starting from head.next, then attach current node at the end.

Key operations after recursive call returns:

• head.next.next = head
• head.next = null

Java Solution

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

        ListNode newHead = reverseList(head.next);
        head.next.next = head;
        head.next = null;
        return newHead;
    }
}

Complexity

• Time: O(n)
• Space: O(n) due to recursion stack

When to Use

Prefer iterative solution in production if stack depth can be large. Recursive version is elegant and useful for interviews and small lists.

Key Takeaways

• Start from the brute-force idea, then derive the optimized invariant.
• Use clean pointer/index boundaries to avoid off-by-one bugs.
• Validate against edge cases (empty input, single element, duplicates, extreme values).