F - Shift and Inversions
Codeforces Round #364 (Div. 2) C. They Are Everywhere
Educational Codeforces Round 15 B. Powers of Two
Educational Codeforces Round 15 C. Cellular Network
Codeforces Round #368 (Div. 2) C. Pythagorean Triples
AIM Tech Round 3 (Div. 2) B. Checkpoints
Window String
Palindrome Partitioning
Subset
Letter Phone