[quenstionsasked]

Haven't taken the time to read through this properly so forgive the question - but is this any different from the above problem?

And if so - if someone solves this programming task on leetcode have they not then also solved the permutation problem from OP?

[robinhouston]

It is different because a safe combination may contain the same digit more than once, so the intended solution is a de Bruijn sequence: https://en.wikipedia.org/wiki/De_Bruijn_sequence