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Reverse a Linked List at Amazon — Interview Guide

How to approach Reverse a Linked List in a Amazon interview: the optimal approach, what Amazon interviewers look for, and company-specific tips.

Updated 2026-09EasyLinked Lists

The problem at Amazon

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

Amazon uses this problem to assess customer-obsessed, data-driven, bar-raising. Expect Amazon-specific follow-ups that tie the solution back to production reasoning and the company's engineering bar.

Key concepts

Maintain a prev pointer (initially null) and a current pointer.
At each step, save next, point current's next at prev, then advance prev and current.
The recursive version reverses the rest first, then points the next node back at the head.

Approach

def reverse(head):
    prev = None
    while head:
        nxt = head.next
        head.next = prev
        prev = head
        head = nxt
    return prev

Complexity

Variant	Time	Space
Iterative	O(n)	O(1)
Recursive	O(n)	O(n) call stack

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