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### How can I print all the numbers from 1 to n in random order?

by vroom (Pope)
 on Jan 17, 2000 at 09:16 UTC Need Help??
Contributed by vroom on Jan 17, 2000 at 09:16 UTC
Q&A  > numbers

 Answer: How can I print all the numbers from 1 to n in random order?contributed by ChrisS I'd use the List::Util module. ```use List::Util qw(shuffle); my \$n = 10; # use \$ARGV[0] or whatever to set \$n print join " ", shuffle(1 .. \$n); [download]``` Answer: How can I print all the numbers from 1 to n in random order?contributed by btrott I don't see the original here, so I don't know if this has been suggested... but you could just stick the numbers in an array, then shuffle the array, then print them. Use the Fisher-Yates Shuffle, which avoids the splice quadratic algorithm bit. ``` sub fisher_yates_shuffle { my \$array = shift; my \$i; for (\$i = @\$array; --\$i; ) { my \$j = int rand (\$i+1); next if \$i == \$j; @\$array[\$i,\$j] = @\$array[\$j,\$i]; } } my \$N = 50; my @array = (1..\$N); fisher_yates_shuffle( \@array ); # permutes @array in place print "@array"; [download]``` From perlfaq4, How do I shuffle an array randomly?. Answer: How can I print all the numbers from 1 to n in random order?contributed by lanval \$ cat numbers.pl ```#!/usr/bin/perl sub RandomiseArray { my (%b, \$c); map { do { \$c = rand } until(!exists \$b{\$c}); \$b{\$c} = \$_ } @_ +; return values(%b); } my @a = RandomiseArray(1..10); print "@a\n"; [download]``` \$ ./numbers.pl 8 5 1 3 10 2 6 4 9 7 \$ ./numbers.pl 4 2 3 9 5 8 6 1 7 10 \$ ./numbers.pl 8 10 7 6 5 9 2 3 4 1 Yeah? Answer: How can I print all the numbers from 1 to n in random order?contributed by chromatic Hmm, see splice for why that doesn't work. Here's the fix: print (splice @a, rand @a, 1);

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