(Re: Algorithm::Combinatorics) the logic in principle can be refined to skip some more permutations, but benchmarks showed no difference whatsoever, so I left the code that is easier to understand and added a comment about it: 

    /* I tried an alternative approach that would in theory avoid the
    generation of some permutations with fixed-points: keeping track of
    the leftmost fixed-point, and reversing the elements to its right.
    But benchmarks up to n = 11 showed no difference whatsoever.
    Thus, I left this version, which is simpler.

    That n = 11 does not mean there was a difference for n = 12, it
    means I stopped benchmarking at n = 11. */

The current interface guarantees lexicographic order, but I plan to provide more algorithms that relax that condition if you don't need it and faster generators are available. I will write it before I die ideally.

In reply to Re^3: Derangements iterator (others) by fxn
in thread Derangements iterator by tye

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