How can you assemble six 1 × 2 × 2 blocks and three 1 × 1 × 1 blocks into a 3 × 3 × 3 cube?
Source: Two Dutch architects: Jan Slothouber and William Graatsma.
The hint was very helpful since, with c in the center, the two other singletons (a and b) c-touching corners could only be in one of three configurations: 1) defining an edge on c, 2) defining a face diagonal on c or 3) defining a volume diagonal on c. I started with the third possibility and it worked!
Here are the layers:
a22 422 466
113 4c3 466
113 553 55b
Edited on September 14, 2018, 10:12 am