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API Helpers & Reliability - C# Practical Coding Problems | Aporeon

C# Practical Coding Problems

API Helpers & Reliability

Validation helpers, rate limiting, retry with cancellation, LRU cache, and log aggregation.

5 drillsPractice one at a timeOrdered pathCoding problem

Recommended start

Fixed Window Limiter

Implements a small in-memory fixed-window rate limiter with per-key counters.

Medium~25 minStep 1 of 5

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1Fixed Window LimiterRecommended startImplements a small in-memory fixed-window rate limiter with per-key counters.Coding problemMedium~25 min.NETC#Practice 2

Practice order

5 drillsOne at a time

1Fixed Window LimiterUp next / Medium / ~25 min
2Date Range ValidationEasy / ~15 min
3Async Retry HelperHard / ~35 min

Date Range Validation

Implements a small validation helper for date ranges with clear error messages.

Coding problemEasy~15 min.NETC#

Practice

3Async Retry HelperImplements a bounded async retry helper that respects cancellation and does not retry every exception blindly.Coding problemHard~35 min.NETC#Practice

4LRU CacheImplements a small LRU cache using a dictionary plus linked list for O(1) get and put.Coding problemHard~35 min.NETC#Practice

5Error AggregationAggregates log entries into per-minute error counts with deterministic output.Coding problemMedium~25 min.NETC#Practice

4

LRU Cache

Hard / ~35 min

5Error AggregationMedium / ~25 min