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HomeLeetCode ProblemsPrison Cells After N Days
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How to Solve Prison Cells After N Days Problem

Master the Prison Cells After N Days LeetCode problem with undetectable real-time assistance. Get instant solutions and explanations during your coding interviews.

Phantom Code 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#957
LeetCode Problem

Prison Cells After N Days

There are 8 prison cells in a row and each cell is either occupied or vacant. Each day, whether the cell is occupied or vacant changes according to the following rules: Note that because the prison is a row, the first and the last cells in the row can't have two adjacent neighbors. You are given an integer array cells where cells[i] == 1 if the ith cell is occupied and cells[i] == 0 if the ith cell is vacant, and you are given an integer n. Return the state of the prison after n days (i.e., n such changes described above).

ArrayHash TableMathBit Manipulation

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Problem Breakdown

Understanding the Prison Cells After N Days Problem

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

Problem Statement

There are 8 prison cells in a row and each cell is either occupied or vacant. Each day, whether the cell is occupied or vacant changes according to the following rules: Note that because the prison is a row, the first and the last cells in the row can't have two adjacent neighbors. You are given an integer array cells where cells[i] == 1 if the ith cell is occupied and cells[i] == 0 if the ith cell is vacant, and you are given an integer n. Return the state of the prison after n days (i.e., n such changes described above).

MediumProblem #957
LeetCode

Prison Cells After N Days

Related Topics

ArrayHash TableMathBit Manipulation

How Phantom Code Helps

Get real-time assistance for Prison Cells After N Days problems during coding interviews. Phantom Code provides instant solutions and explanations.

Examples

# Example 1

Input
cells = [0,1,0,1,1,0,0,1], n = 7
Output
[0,0,1,1,0,0,0,0]

# Example 2

Input
cells = [1,0,0,1,0,0,1,0], n = 1000000000
Output
[0,0,1,1,1,1,1,0]

Constraints

cells.length == 8
cells[i] is either 0 or 1.
1 <= n <= 109

How Phantom Code Helps with LeetCode Problems

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See Phantom Code in Action

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Solve Prison Cells After N Days — There are 8 prison cells in a row and each cell is either occupied or vacant. Ea...

Here's the optimal approach using Array:

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

Time: O(n)  |  Space: O(n)

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Undetectability Checklist

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Platform Compatibility

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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 Prison Cells After N Days and using Phantom Code during coding interviews.

How does Phantom Code help me solve coding problems like Prison Cells After N Days 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 Prison Cells After N Days?
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 Prison Cells After N Days?
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 Prison Cells After N Days 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 Prison Cells After N Days 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 Prison Cells After N Days 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 Prison Cells After N Days 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 Prison Cells After N Days 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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