September Challenge 2016
Faded Palindromes, Chef and digits of a number
November Challenge 2016
Chef and squares, Task for Alexey
October Cook-Off 2016
Watson asks Does Permutation Exist, ChefWatson uses Social Network
February Challenge 2017
Chef and His Apartment Dues
March Challenge 2017
Xenny and Alternating Tasks, Bear and Extra Number
September Challenge 2017
Sereja and Commands, Little Chef and Sums, Minimum Good Permutation, Chef and Pick Digit
September Cook-Off 2017
Infinite OR Game, Statistics Construction, Subsequence Equality
February Challenge 2020 Division 2
No Change Required, School of Geometry
India