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HomeLeetCode ProblemsReverse Nodes in Even Length Groups
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How to Solve Reverse Nodes in Even Length Groups Problem

Master the Reverse Nodes in Even Length Groups LeetCode problem with undetectable real-time assistance. Get instant solutions and explanations during your coding interviews.

PhantomCodeAI generates complete solutions and debugging hints that you can use while explaining your approach, so you stay calm and in control.

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Medium#2074
LeetCode Problem

Reverse Nodes in Even Length Groups

You are given the head of a linked list. The nodes in the linked list are sequentially assigned to non-empty groups whose lengths form the sequence of the natural numbers (1, 2, 3, 4, ...). The length of a group is the number of nodes assigned to it. In other words, Note that the length of the last group may be less than or equal to 1 + the length of the second to last group. Reverse the nodes in each group with an even length, and return the head of the modified linked list.

Linked List

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Problem Breakdown

Understanding the Reverse Nodes in Even Length Groups Problem

Let's break down this LeetCode problem and understand what makes it challenging in interview settings.

Problem Statement

You are given the head of a linked list. The nodes in the linked list are sequentially assigned to non-empty groups whose lengths form the sequence of the natural numbers (1, 2, 3, 4, ...). The length of a group is the number of nodes assigned to it. In other words, Note that the length of the last group may be less than or equal to 1 + the length of the second to last group. Reverse the nodes in each group with an even length, and return the head of the modified linked list.

MediumProblem #2074
LeetCode

Reverse Nodes in Even Length Groups

Related Topics

Linked List

How PhantomCodeAI Helps

Get real-time assistance for Reverse Nodes in Even Length Groups problems during coding interviews. PhantomCodeAI provides instant solutions and explanations.

Examples

# Example 1

Input
head = [5,2,6,3,9,1,7,3,8,4]
Output
[5,6,2,3,9,1,4,8,3,7]

# Example 2

Input
head = [1,1,0,6]
Output
[1,0,1,6]

# Example 3

Input
head = [1,1,0,6,5]
Output
[1,0,1,5,6]

Constraints

The number of nodes in the list is in the range [1, 105].
0 <= Node.val <= 105

How PhantomCodeAI Helps with LeetCode Problems

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Solve Reverse Nodes in Even Length Groups — You are given the head of a linked list. The nodes in the linked list are sequen...

Here's the optimal approach using Linked List:

def solve(input):
# Optimal O(n) solution
return result

Time: O(n)  |  Space: O(n)

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Undetectability Checklist

Run compatibility test before interviews
Use recommended Zoom version settings
Enable advanced screen capture options
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Platform Compatibility

Zoom
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Google Meet
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HackerRank
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CodeSignal
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CoderPad
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User results and traction

Thousands of developers use PhantomCodeAI. Social proof signals that this approach helps real candidates land offers across a range of companies.

Undetectability and technical details

Our native desktop architecture avoids common detection vectors used by browser extensions. We provide a clear checklist so you can run basic checks and confirm the app will be invisible.

Platform compatibility and limitations

We work with Zoom, HackerRank, CodeSignal, CoderPad and other web-based platforms. Check the compatibility note and request a browser link if a specific desktop app is unsupported.

Frequently Asked Questions

Common questions about solving Reverse Nodes in Even Length Groups and using PhantomCodeAI during coding interviews.

How does PhantomCodeAI help with LeetCode problems during a coding interview?
PhantomCodeAI reads the problem from a screenshot or listens to it via audio, then generates a complete solution with a step-by-step approach and time/space complexity, so you can focus on explaining your reasoning rather than getting stuck on implementation.
Which programming languages does PhantomCodeAI support?
11 languages including Python, Java, C++, JavaScript, TypeScript, Go, Rust, Ruby, Swift, Kotlin, and C#. Set a preferred language to get idiomatic solutions.
Does PhantomCodeAI work with HackerRank, CodeSignal, and CoderPad?
Yes — it works alongside LeetCode, HackerRank, CodeSignal, CoderPad, and HackerEarth, plus any browser-based coding environment.
Can PhantomCodeAI handle follow-up questions and modifications?
Yes. Capture the modified problem by screenshot or audio and get an updated solution within seconds, including new edge cases and optimizations.
Is PhantomCodeAI detectable during live interviews?
PhantomCodeAI runs as a native desktop overlay that does not appear in screen shares, recordings, or proctoring software, and works with Zoom, Google Meet, Microsoft Teams, and major coding platforms.
Should I still practice these problems on my own first?
Yes. The most durable preparation is solving problems unaided first, then using AI afterward to review your approach, complexity, and missed edge cases — use it to debrief and learn, not to skip the reps.

Related LeetCode Problems

Practice more problems similar to Reverse Nodes in Even Length Groups.

2Add Two NumbersMedium19Remove Nth Node From End of ListMedium21Merge Two Sorted ListsEasy23Merge k Sorted ListsHard24Swap Nodes in PairsMedium25Reverse Nodes in k-GroupHard61Rotate ListMedium82Remove Duplicates from Sorted List IIMedium
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