Question

Given an X, what math is needed to find its Y, using this table?

x	y
0	1
1	0
2	6
3	5
4	4
5	3
6	2

This is a language agnostic problem. I can’t just store the array, and do the lookup. The input will always be the finite set of 0 to 6. It won’t be scaling later.

Answer 1

This:

y = (8 - x) % 7

This is how I arrived at that:

x  8-x  (8-x)%7
----------------
0   8     1
1   7     0
2   6     6
3   5     5
4   4     4
5   3     3
6   2     2