January Challenge 2015
Sereja and Number Division 2, Chef and Stones, Sereja and Votes, Gcd Queries
February Challenge 2015
Chef and Chain, Chef and Strange Formula, Let us play with rank list, Chef and Equality
March Challenge 2015
Sign Wave, Chef and Notebooks
April Challenge 2015
Chef and Interview, Broken Telephone, Division of Lands, Chef and Piano Scales
July Challenge 2015
Bread, Na2a and lucky stone, Chef and Cube
August Challenge 2015
Way Out, Aditi and Magic Trick, Gravity Guy, Cooking Machine
September Challenge 2015
Chain of Doughnuts, Count Steps in Matrix, Bank robbery, Lighthouses, Cracking the Code
October Challenge 2015
Who dares to be a millionaire, Rupsa and Equilateral Triangle, Spheres, Count Subarrays, Time measure
May Cook-Off 2015
Devu and friendship testing
July Cook-Off 2015
Cops and the Thief Devu, Maximize Disjoint Pair Sum
August Cook-Off 2015
Chef and the XORed Number , Chef and the Wildcard Matching
India