December Challenge 2018 Division 2
(Challenge) Delete DAG, Chef and An Ideal Problem, Chef and Interactive Contests, Chef and Interactive XOR, Max and Electrical Panel, Chef and Meatballs
November Challenge 2018 Division 2
Chef and Happiness, Chef and Difficult Contests, Magician versus Chef 2, Chef, Primes and Trees (Challenge), Good Median, Appy Loves One, Chef and Ridges
February Challenge 2019 Division 1
Manhattan Rectangle, Guess It Right, Chef and Secret Ingredients, Yet Another Tree Problem, Art of Balance
March Challenge 2019 Division 1
Yet Again a Subarray Problem
April Challenge 2019 Division 1
Playing with Numbers, Subtree Removal
April Lunchtime 2019 Division 1
Firdavs and Planet F, Minimum Sum
May Challenge 2019 Division 1
Ada Rooks 2, Where to Build the Roads
June Challenge 2019 Division 1
Lent Money, Chef and Ingredients, Intersecting Paths, Sum and GCD
January Challenge 2020 Division 1
English, Chefina and Prefix Suffix Sums, Doraemon, Chef and Dynamo
February Challenge 2020 Division 1
Chef and Railway Stations, Expected Change, No Change Required, Long Contest and Cook Off Overlaps
March Challenge 2020 Division 1
Chef and DAG, Break, Lasers Everywhere, Lasers Everywhere Alternative
Vietnam