May Challenge 2017
Chef and Battleship, Chef and Sub Array
June Challenge 2017
Chef and Prime Queries, A Good Set, Xenny and Coin Rankings, Pairwise union of sets
August Long Challenge 2017
Chef and Rainbow Array, Chef And Fibonacci Array, Chef and Mover, Palindromic Game, Greedy Candidates, Strings and Graphs
January Challenge 2018
K-Concatenation, Maximum Score, Rectangle, String Merging, Partition the numbers
December Cook-Off 2018 Division 1
Swag Subsets, Yalalovichik Numbers, Yalalovichik Strings
October Lunchtime 2018 Division 1
Coloring the Grid, Weird Question
Russia