2017 was a prime year with great contests and some notorious coincidences.
From the problems that I proposed, my favourite was BCYCLES, it is about covering twice every edge of a bicubic graph using cycles. The idea was colouring the edges with 3 colours and then make the cycles using alternating colours.
From problems that I saw in CodeForces my favourite was Symmetric Projections, IMHO it is not a hard problem, but I liked the property that every axis with momentum 0 passes through the center of mass.
