Three, Three, No code-golf restricted-complexity Given a non-empty sequence of non-negative integers, output any permutation of it in which no two adjacent elements have a sum that is divisible by 3. If it is impossible, either crash the program, return an empty sequence, or output nothing. The ...

The small code sample 42&x==42 which checks if a certain bit or all bits in a bitmask is set in an int feels like something that should be golf-able, but I'm stuck. Any hints? For large numbers, deduplicating the number should be a win, right? Maybe there's something useful to be done for smaller...

Consider the sequence \$(a_n)\$ defined in the following way. \$a_0=0\$ For all \$n=1, 2, 3, \dots\$, define \$a_n\$ to be the smallest positive integer such that \$a_n-a_i\$ is not a square number, for any \$0\leq i<n\$ In other words, this is the lexicographically first sequence where no two ...

I'm aware that this phenomenon is nothing new, as OEIS Challenges have been around since the beginning of this site. And I also don't think OEIS challenges are necessarily bad. In fact, many of my favorite challenges on this site are just those. But in the past year, I've noticed a large uptick i...

Let's rise higher! answer-chaining, number, restricted-source (I am posting this challenge in sandbox because this kind of exceptional challenges are often closed, and then downvoted to oblivion, so I want to get your feedback and with kind help you fix the specifications in this challenge, and m...

How to Hash a 2d maze of size less than 10 to maintain state while dfs