Introductory

1. weird-algorithm
2. missing-number
3. repetitions
4. increasing-array
5. permutations
6. number-spiral
7. two-knights
8. two-sets
9. bit-strings
10. trailing-zeros
11. coin-piles
12. palindrome-reorder
13. gray-code
14. tower-of-hanoi
15. creating-strings
16. apple-division
17. chessboard-and-queens
18. digit-queries
19. grid-paths