Fancy That!
Educational Codeforces Round 61 (Rated for Div. 2) F. Clear the String
Codeforces Round 549 (Div. 1) B. Lynyrd Skynyrd
Forethought Future Cup - Final Round (Onsite Finalists Only) C. Thanos Nim
Educational Codeforces Round 64 (Rated for Div. 2) C. Match Points
Codeforces Round 555 (Div. 3) F. Maximum Balanced Circle
Escape from grid
Minimum transactions
Minimum cost
Queries problem