Nice kata, well done.

Approved

python new test framework is required. updated in this fork

C Translation (author inactive).

It's solvable (just pasted and re-run my solution), with the right method I assume !

impossible to solve in Ruby

My god.... I need to revise my method for finding cubes... Sorry, and thank you :)

729 (9^3) and 216 (6^3) are both cubes. You're supposed to return the number of lucky sevens so 2 is correct.

I've spent a long moment trying to understand, but I can't get it. Is it ok that we are supposed to add all surrounding numbers and check if the result is a cube? That's what I understand from the description and the provided examples, but it does not match with the tests.
In Python, first test case: there are two sevens, one is surrounded by 72, 229, 355, 73, sum is 729=6^3, ok, the other is surrounded by 169, 3,13,31, sum is 216, and is not a cube. Neither is any sum of combinations of those numbers, or any of them. However we're supposed to return 2. What's the point?

A very clever solution. This helped me understand reduce better.

This one really tested my patience. Nice kata!

Yeah, works now. Thanks!

Should be fixed now.

I think its fixed now, so sorry about this. Please try again.