Hi all,

I'm a bit lost and possibly because that's my first time in this kind of problem solving "games" (note that I started with the problem 165 and now tried this problem 166, I didn't go through all the games).

I "solved" this problem by generating the matrices and checking but I can't really consider this solved since with all the caching or improvements I tried, I cannot compute the result for digits above 3 (1 is almost immediate, 2 takes 2 seconds on my laptop and 3 takes around 60s, 4 is exponentially longer and so forth).

I understand that I'm NOT on my way to really solve this! Whatever optimization I could come up with will likely not reduce enough the computation time to address 7.

I tried to read on criss-cross Euler on the web but can't really understand the relationship between the matrices and the polyhedrons faces, edges and vertices.

So, my questions are the following: Should I go through the exercises in order to 'discover' Euler along the path?

1. Should I go through the exercises in order to 'discover' Euler along the path?
2. This exercise is tagged "Easy", did I miss something completely?
3. Is there a paper that I didn't find clarifying the relationship Euler/matrices?

Thanks! JC