Skip to content

Tracks Drills Topics Technologies Tech stacks Skill areas

Tracks Drills Topics

Loading

Aporeon interview preparation

About Privacy Terms

Coding Practice

Practical C# coding problems with examples, constraints, solutions, complexity, and edge-case thinking.

18 drillsPractice one at a timeOrdered pathCoding problem

Recommended start

Word Frequency

Implements a word-frequency counter with normalization, punctuation handling, and stable ordering.

Easy~15 minStep 1 of 18

Practice this drill Choose another

Search

18 of 18 shown

1Word FrequencyRecommended startImplements a word-frequency counter with normalization, punctuation handling, and stable ordering.Coding problemEasy~15 min.NETC#Practice 2First Unique Character

Practice order

18 drillsOne at a time

1Word FrequencyUp next / Easy / ~15 min
2First Unique CharacterEasy / ~15 min
3Group OrdersMedium / ~25 min
4

Implements a stable first-unique-character search using counts and original order.

Coding problemEasy~15 min.NETC#

Practice

3Group OrdersBuilds customer summaries from order rows using grouping, aggregation, and deterministic ordering.Coding problemMedium~25 min.NETC#Practice

4Dedupe EventsImplements duplicate suppression while preserving the first event for each idempotency key.Coding problemMedium~25 min.NETC#Practice

5Merge Time RangesImplements interval merging for scheduling-style time ranges with sorted output.Coding problemMedium~25 min.NETC#Practice

6Top K FrequentImplements top-K frequency selection with deterministic tie-breaking.Coding problemMedium~25 min.NETC#Practice

7Flatten Tree PathsFlattens a tree into display paths while preserving order and preventing simple cycles.Coding problemMedium~25 min.NETC#Practice

8Paged Result HelperImplements a safe in-memory paging helper with metadata and boundary handling.Coding problemEasy~15 min.NETC#Practice

9Parse FiltersParses a simple filter expression into a validated dictionary without accepting arbitrary keys.Coding problemMedium~25 min.NETC#Practice

10Date Range ValidationImplements a small validation helper for date ranges with clear error messages.Coding problemEasy~15 min.NETC#Practice

11Fixed Window LimiterImplements a small in-memory fixed-window rate limiter with per-key counters.Coding problemMedium~25 min.NETC#Practice

12Async Retry HelperImplements a bounded async retry helper that respects cancellation and does not retry every exception blindly.Coding problemHard~35 min.NETC#Practice

13LRU CacheImplements a small LRU cache using a dictionary plus linked list for O(1) get and put.Coding problemHard~35 min.NETC#Practice

14Error AggregationAggregates log entries into per-minute error counts with deterministic output.Coding problemMedium~25 min.NETC#Practice

15Version CompareImplements comparison for simple semantic version strings with missing patch parts treated as zero.Coding problemMedium~25 min.NETC#Practice

16Invoice TotalImplements invoice total calculation with quantity, unit price, percentage discount, and rounding.Coding problemMedium~25 min.NETC#Practice

17Redact Log DataImplements safe redaction of known sensitive keys in a dictionary before logging.Coding problemMedium~25 min.NETC#Practice

18Batch ChunkingImplements chunking for batch processing without dropping final partial batches.Coding problemEasy~15 min.NETC#Practice

Dedupe Events

Medium / ~25 min

5Merge Time RangesMedium / ~25 min

6Top K FrequentMedium / ~25 min

7Flatten Tree PathsMedium / ~25 min

8Paged Result HelperEasy / ~15 min

+10 more drills in this section

Coding Practice - .NET Backend | Aporeon