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How to Solve Copy List with Random Pointer Problem
Master the Copy List with Random Pointer LeetCode problem with undetectable real-time assistance. Get instant solutions and explanations during your coding interviews.
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Start Free for WindowsMedium#138
LeetCode ProblemCopy List with Random Pointer
A linked list of length n is given such that each node contains an additional random pointer, which could point to any node in the list, or null. Construct a deep copy of the list. The deep copy should consist of exactly n brand new nodes, where each new node has its value set to the value of its corresponding original node. Both the next and random pointer of the new nodes should point to new nodes in the copied list such that the pointers in the original list and copied list represent the same list state. None of the pointers in the new list should point to nodes in the original list. For example, if there are two nodes X and Y in the original list, where X.random --> Y, then for the corresponding two nodes x and y in the copied list, x.random --> y. Return the head of the copied linked list. The linked list is represented in the input/output as a list of n nodes. Each node is represented as a pair of [val, random_index] where: Your code will only be given the head of the original linked list.
Hash TableLinked List
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Problem Breakdown
Understanding the Copy List with Random Pointer Problem
Let's break down this LeetCode problem and understand what makes it challenging in interview settings.
Problem Statement
A linked list of length n is given such that each node contains an additional random pointer, which could point to any node in the list, or null. Construct a deep copy of the list. The deep copy should consist of exactly n brand new nodes, where each new node has its value set to the value of its corresponding original node. Both the next and random pointer of the new nodes should point to new nodes in the copied list such that the pointers in the original list and copied list represent the same list state. None of the pointers in the new list should point to nodes in the original list. For example, if there are two nodes X and Y in the original list, where X.random --> Y, then for the corresponding two nodes x and y in the copied list, x.random --> y. Return the head of the copied linked list. The linked list is represented in the input/output as a list of n nodes. Each node is represented as a pair of [val, random_index] where: Your code will only be given the head of the original linked list.
MediumProblem #138
LeetCodeCopy List with Random Pointer
Related Topics
Hash TableLinked List
How Phantom Code Helps
Get real-time assistance for Copy List with Random Pointer problems during coding interviews. Phantom Code provides instant solutions and explanations.
Examples
# Example 1
Input
head = [[7,null],[13,0],[11,4],[10,2],[1,0]]
Output
[[7,null],[13,0],[11,4],[10,2],[1,0]]
# Example 2
Input
head = [[1,1],[2,1]]
Output
[[1,1],[2,1]]
# Example 3
Input
head = [[3,null],[3,0],[3,null]]
Output
[[3,null],[3,0],[3,null]]
Constraints
0 <= n <= 1000
-104 <= Node.val <= 104
Node.random is null or is pointing to some node in the linked list.
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Solve Copy List with Random Pointer — A linked list of length n is given such that each node contains an additional ra...
Here's the optimal approach using Hash Table:
def solve(input):
# Optimal O(n) solution
return result
Time: O(n) | Space: O(n)
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Frequently Asked Questions
Common questions about solving Copy List with Random Pointer and using Phantom Code during coding interviews.
How does Phantom Code help me solve coding problems like Copy List with Random Pointer during interviews?
Phantom Code generates complete solutions instantly with proper complexity analysis, letting you focus on explaining your approach and demonstrating problem-solving skills rather than getting stuck on implementation details during high-pressure situations.
What if the interviewer asks follow-up questions or modifications to problems like Copy List with Random Pointer?
Phantom Code adapts in real-time. Screenshot the modified problem or use audio mode to capture the interviewer's follow-up, and get an updated solution within seconds — including edge cases and optimizations.
Can Phantom Code help me communicate my solution for problems like Copy List with Random Pointer?
Yes. Phantom Code provides step-by-step approach explanations with 3 progressive thoughts, so you can walk through your solution naturally. It also provides time and space complexity analysis to discuss trade-offs.
How does Phantom Code assist with different programming languages for Copy List with Random Pointer type problems?
Phantom Code supports 11 programming languages including Python, Java, C++, JavaScript, TypeScript, Go, Rust, Ruby, Swift, Kotlin, and C#. Set your preferred language and get idiomatic solutions.
What coding mistakes does Phantom Code help me avoid during Copy List with Random Pointer interviews?
Phantom Code catches common mistakes like off-by-one errors, missing edge cases, incorrect base conditions, and suboptimal approaches. It provides clean, well-structured code that handles all edge cases.
Is Phantom Code detectable when solving problems like Copy List with Random Pointer during live interviews?
No. Phantom Code runs as an invisible desktop overlay that doesn't appear in screen shares, recordings, or proctoring software. It works with Zoom, HackerRank, CodeSignal, CoderPad, and all major platforms.
How does Phantom Code help when I'm struggling with Copy List with Random Pointer style questions under pressure?
The AI provides structured guidance: first the approach (what algorithm/data structure to use and why), then the implementation with clean code, and finally complexity analysis. This helps you think clearly even under pressure.
Does Phantom Code work for the coding platforms used in Copy List with Random Pointer interviews?
Yes. Phantom Code works with all major coding platforms including LeetCode, HackerRank, CodeSignal, CoderPad, HackerEarth, and any browser-based coding environment.
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