Re^7: Algorithm RFC: fast (pseudo-)random shuffle with no repetition

So this aren’t valid permutations?

karl@h3002993:~/src/perl$ ./pmute.pl
1 8 1 2 1 7 1 3 1 6 1 5 1 4 1
karl@h3002993:~/src/perl$ ./pmute.pl
1 3 1 4 1 7 1 5 1 2 1 6 1 8 1
karl@h3002993:~/src/perl$ ./pmute.pl
1 4 1 8 1 6 1 5 1 3 1 2 1 7 1
karl@h3002993:~/src/perl$ ./pmute.pl
1 5 1 8 1 2 1 4 1 6 1 3 1 7 1
karl@h3002993:~/src/perl$ ./pmute.pl
1 7 1 5 1 4 1 3 1 8 1 2 1 6 1
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FYI

karl@h3002993:~/src/perl$ time ./pmute.pl
1 4 1 3 1 2 1 6 1 5 1 7 1 8 1

real    0m0,081s
user    0m0,076s
sys     0m0,004s

karl@h3002993:~/src/perl$ lscpu
 Architecture:        x86_64
CPU op-mode(s):      32-bit, 64-bit
Address sizes:       46 bits physical, 48 bits virtual
Byte Order:          Little Endian
CPU(s):              1
On-line CPU(s) list: 0
Vendor ID:           GenuineIntel
Model name:          Intel(R) Xeon(R) CPU E5-2680 v3 @ 2.50GHz
…
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Comment on Re^7: Algorithm RFC: fast (pseudo-)random shuffle with no repetition Select or Download Code

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Re^8: Algorithm RFC: fast (pseudo-)random shuffle with no repetition by LanX (Saint) on Sep 24, 2023 at 17:49 UTC
> So this aren’t valid permutations? They are. Mea culpa. You are listing the permutations of the fillers between the fixed 1s, hence 7! valid solutions. See Re^8: Algorithm RFC: fast (pseudo-)random shuffle with no repetition for what I meant and try `(1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2)` instead. If this doesn't convince you that try-and-error isn't a good idea, try adding even more 1s and 2s. Cheers Rolf _{(addicted to the Perl Programming Language :) see Wikisyntax for the Monastery}	[reply] [d/l]

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Re^8: Algorithm RFC: fast (pseudo-)random shuffle with no repetition
by LanX (Saint) on Sep 24, 2023 at 17:49 UTC

> So this aren’t valid permutations?

They are. Mea culpa.

You are listing the permutations of the fillers between the fixed 1s, hence 7! valid solutions.

See Re^8: Algorithm RFC: fast (pseudo-)random shuffle with no repetition for what I meant and try (1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2) instead.

If this doesn't convince you that try-and-error isn't a good idea, try adding even more 1s and 2s.

Cheers Rolf
_{(addicted to the Perl Programming Language :)

see Wikisyntax for the Monastery}

[reply]
[d/l]