use slice for both swaps

1 files changed, 20 insertions, 17 deletions

diff --git a/challenge-134/james-smith/perl/ch-1.pl b/challenge-134/james-smith/perl/ch-1.pl
index d18ca48222..665acde010 100644
--- a/challenge-134/james-smith/perl/ch-1.pl
+++ b/challenge-134/james-smith/perl/ch-1.pl
@@ -8,30 +8,33 @@ use Test::More;
 use Benchmark qw(cmpthese timethis);
 use Data::Dumper qw(Dumper);
 
-my $S = 10;
-my @s = (1,0,2..$S-1); ## Cheat we jump into the first pemutation which
-                       ## doesn't start with a "0" 1023456789 - avoids
-                       ## us having to check for a leading 0...
-my $count=5;
-
-do {
-  say @s;
-} while next_perm && --$count;
-
+my @s = (0,reverse 1..9); ## Cheat we start with the last perumation
+                          ## starting with 0 - 0987654321
+                          ## Saves us looping through the first
+                          ## combinations checking for number starting
+                          ## with non-zero (362880 combinations)
+my $count = @ARGV ? $ARGV[0] : 5;
 
 sub next_perm {
-  my($i,$j,$p);
+  my( $i, $j );
+
   ## Find largest index for which Si+1 > Si
-  ( $s[$_] < $s[$_+1] ) && ( $i=$_ ) foreach 0 .. $S-2;    ## Find i
+  ( $s[$_] < $s[$_+1] ) && ( $i = $_ ) foreach 0 .. @s-2;    ## Find i
 
   return unless defined $i; ## Got to the end of the list of permutations
 
   ## Find latest index for which Sj > Si for j>i
-  ( $s[$i] < $s[$_]   ) && ( $j=$_ ) foreach $i+1 .. $S-1; ## Find j
+  ( $s[$i] < $s[$_]   ) && ( $j = $_ ) foreach $i+1 .. @s-1; ## Find j
+
+  ## Flip ith & jth elements..., then all numbers greater than i..
+  @s[ $i, $j       ] = @s[ $j, $i               ];
+  @s[ $i+1 .. @s-1 ] = @s[ reverse $i+1 .. @s-1 ];
 
-  ## Flip i & jth elements..., then all numbers greater than i..
-  ( $s[$i], $s[$j] ) = ( $s[$j], $s[$i] );               ## Flip numbers over...
-  @s[ $i+1 .. $S-1 ] = @s[ reverse $i+1 .. $S-1 ];       ## Flip remaining list
-  return 1;
+  return 1; ## Return true to say can continue...
 }
 
+
+say @s while next_perm && $count--;
+
+
+