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How to Solve Invalid Transactions Problem
Master the Invalid Transactions LeetCode problem with undetectable real-time assistance. Get instant solutions and explanations during your coding interviews.
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Start Free for WindowsMedium#1169
LeetCode ProblemInvalid Transactions
A transaction is possibly invalid if: You are given an array of strings transaction where transactions[i] consists of comma-separated values representing the name, time (in minutes), amount, and city of the transaction. Return a list of transactions that are possibly invalid. You may return the answer in any order.
ArrayHash TableStringSorting
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Problem Breakdown
Understanding the Invalid Transactions Problem
Let's break down this LeetCode problem and understand what makes it challenging in interview settings.
Problem Statement
A transaction is possibly invalid if: You are given an array of strings transaction where transactions[i] consists of comma-separated values representing the name, time (in minutes), amount, and city of the transaction. Return a list of transactions that are possibly invalid. You may return the answer in any order.
MediumProblem #1169
LeetCodeInvalid Transactions
Related Topics
ArrayHash TableStringSorting
How Phantom Code Helps
Get real-time assistance for Invalid Transactions problems during coding interviews. Phantom Code provides instant solutions and explanations.
Examples
# Example 1
Input
transactions = ["alice,20,800,mtv","alice,50,100,beijing"]
Output
["alice,20,800,mtv","alice,50,100,beijing"]
# Example 2
Input
transactions = ["alice,20,800,mtv","alice,50,1200,mtv"]
Output
["alice,50,1200,mtv"]
# Example 3
Input
transactions = ["alice,20,800,mtv","bob,50,1200,mtv"]
Output
["bob,50,1200,mtv"]
Constraints
transactions.length <= 1000
Each transactions[i] takes the form "{name},{time},{amount},{city}"
Each {name} and {city} consist of lowercase English letters, and have lengths between 1 and 10.
Each {time} consist of digits, and represent an integer between 0 and 1000.
Each {amount} consist of digits, and represent an integer between 0 and 2000.
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Solve Invalid Transactions — A transaction is possibly invalid if: You are given an array of strings transact...
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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HackerRank
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Frequently Asked Questions
Common questions about solving Invalid Transactions and using Phantom Code during coding interviews.
How does Phantom Code help me solve coding problems like Invalid Transactions 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 Invalid Transactions?
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 Invalid Transactions?
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 Invalid Transactions 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 Invalid Transactions 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 Invalid Transactions 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 Invalid Transactions 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 Invalid Transactions 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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