Level 3

Advanced · Structure and efficiency

Use AI and search freely. Choose a problem by level; starting it records a separate timed attempt. Each problem is graded on accuracy (50), performance (30), and time (20).

1. 3-190 min

   Dependency execution order

   Produce a valid execution order and detect cycles.

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2. 3-290 min

   Lowest-cost routes

   Find minimum reachable costs in a directed graph.

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3. 3-390 min

   LRU cache simulator

   Implement a capacity-limited cache that tracks recency.

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4. 3-490 min

   Sliding-window rate limiter

   Limit requests within each user’s sliding time window.

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5. 3-590 min

   Repair an expiring cache

   Fix expiration boundaries, updates, and recency in an existing cache.

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