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.NET Full Stack

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

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

Practice order

18 drillsOne at a time

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