Interview practice

Twenty timed coding problems, from warm-ups to hard.

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1. 1Rotate a listEasy · 10 min
2. 2Balanced bracketsEasy · 15 min
3. 3First character seen onceEasy · 10 min
4. 4A pair that hits the targetEasy · 15 min
5. 5Palindrome through the noiseEasy · 15 min
6. 6The shared defaultEasy · 10 min
7. 7Closures in a loopEasy · 10 min
8. 8Merge intervalsMedium · 20 min
9. 9Group by lettersMedium · 20 min
10. 10Longest run with no repeatsMedium · 25 min
11. 11Count pairs below a limitMedium · 20 min
12. 12Tree level by levelMedium · 20 min
13. 13Fewest hopsMedium · 20 min
14. 14Count connected groupsMedium · 20 min
15. 15Exact changeMedium · 25 min
16. 16Tiling with memoizationMedium · 20 min
17. 17Cheapest routeHard · 35 min
18. 18Edit distanceHard · 35 min
19. 19Best path in a treeHard · 40 min
20. 20Limit concurrent jobsHard · 40 min