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How to Solve Longest Arithmetic Subsequence of Given Difference Problem
Master the Longest Arithmetic Subsequence of Given Difference LeetCode problem with undetectable real-time assistance. Get instant solutions and explanations during your coding interviews.
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Start Free for WindowsMedium#1218
LeetCode ProblemLongest Arithmetic Subsequence of Given Difference
Given an integer array arr and an integer difference, return the length of the longest subsequence in arr which is an arithmetic sequence such that the difference between adjacent elements in the subsequence equals difference. A subsequence is a sequence that can be derived from arr by deleting some or no elements without changing the order of the remaining elements.
ArrayHash TableDynamic Programming
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Problem Breakdown
Understanding the Longest Arithmetic Subsequence of Given Difference Problem
Let's break down this LeetCode problem and understand what makes it challenging in interview settings.
Problem Statement
Given an integer array arr and an integer difference, return the length of the longest subsequence in arr which is an arithmetic sequence such that the difference between adjacent elements in the subsequence equals difference. A subsequence is a sequence that can be derived from arr by deleting some or no elements without changing the order of the remaining elements.
MediumProblem #1218
LeetCodeLongest Arithmetic Subsequence of Given Difference
Related Topics
ArrayHash TableDynamic Programming
How Phantom Code Helps
Get real-time assistance for Longest Arithmetic Subsequence of Given Difference problems during coding interviews. Phantom Code provides instant solutions and explanations.
Examples
# Example 1
Input
arr = [1,2,3,4], difference = 1
Output
4
# Example 2
Input
arr = [1,3,5,7], difference = 1
Output
1
# Example 3
Input
arr = [1,5,7,8,5,3,4,2,1], difference = -2
Output
4
Constraints
1 <= arr.length <= 105
-104 <= arr[i], difference <= 104
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Solve Longest Arithmetic Subsequence of Given Difference — Given an integer array arr and an integer difference, return the length of the l...
Here's the optimal approach using Array:
def solve(input):
# Optimal O(n) solution
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Time: O(n) | Space: O(n)
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Frequently Asked Questions
Common questions about solving Longest Arithmetic Subsequence of Given Difference and using Phantom Code during coding interviews.
How does Phantom Code help me solve coding problems like Longest Arithmetic Subsequence of Given Difference 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 Longest Arithmetic Subsequence of Given Difference?
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 Longest Arithmetic Subsequence of Given Difference?
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 Longest Arithmetic Subsequence of Given Difference 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 Longest Arithmetic Subsequence of Given Difference 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 Longest Arithmetic Subsequence of Given Difference 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 Longest Arithmetic Subsequence of Given Difference 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 Longest Arithmetic Subsequence of Given Difference 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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