all levels · 26 questions · ~39 min
Time complexity · drill
Read a snippet, pick its Big-O. The reverse direction of live coding — train your eye on the access patterns that drive runtime.
0 / 26 passed
- 01Get the first element
- 02Cache hit check before a slow API call
- 03Total up an order
- 04Find a price tier in a sorted ladder
- 05Build every gift-pair combination
- 06Merge two product lists into one
- 07Sort orders by date — divide and conquer
- 08Find three discount codes that sum to a total
- 09Fibonacci — the recursive trap
- 10Fibonacci, but with a cache
- 11List every order the team can be photographed in
- 12How many doublings until n customers?
- 13Build a list of placeholders for n table rows
- 14Detect duplicate emails in a signup list
- 15Render n CSV rows by string concatenation
- 16Sum every cell in a seat-map grid
- 17Dedupe a signup list by email
- 18Dedupe a signup list — the fast version
- 19Find two prices that sum to a coupon target
- 20Filter blocked users out of a chat list
- 21Build a running list with immutable spread
- 22Group orders by status for a dashboard
- 23Walk a comment thread breadth-first
- 24Build a category tree from a flat list
- 25Tags shared between two articles
- 26Slice page 7 out of a 100k-row table