Merge pull request #5966 from drbaggy/master

Lots of stuff!

1 files changed, 26 insertions, 4 deletions

diff --git a/challenge-160/james-smith/perl/ch-2.pl b/challenge-160/james-smith/perl/ch-2.pl
index 317e6031c9..184854564e 100644
--- a/challenge-160/james-smith/perl/ch-2.pl
+++ b/challenge-160/james-smith/perl/ch-2.pl
@@ -6,22 +6,44 @@ use warnings;
 use feature qw(say);
 use Test::More;
 
-my @TESTS = (
+my @TESTS_POS = (
   [ [1,3,5,7,9],  3 ],
   [ [1,2,3,4,5], -1 ],
   [ [2,4,2],      1 ],
-  [ [1,-1,1],     0 ], ## Not sure if -ve values allowed?
+  [ [1..51,1275],50 ],
+);
 
+my @TESTS = (
+  @TESTS_POS,
+  [ [1,-1,1],     0 ], ## Not sure if -ve values allowed?
+  [ [-2,4,-2,1],  3 ],
 );
 
-is( equilibrium_index(@{$_->[0]}), $_->[1] ) foreach @TESTS;
+is( equilibrium_index(         @{$_->[0]}), $_->[1] ) foreach @TESTS;
+is( equilibrium_index_positive(@{$_->[0]}), $_->[1] ) foreach @TESTS_POS;
 
 done_testing();
 
+## This doesn't assume anything about sign of values;
+##
+## There is a possible optimization if you only allow
+## positive values that you can return -1 if $s<$_[$_]
+## as once you have passed the balance point you can
+## stop.
+
 sub equilibrium_index {
   my $s = 0;
   $s += $_ for @_;
-  ($s==$_[$_]) ? (return $_) : ($s-=2*$_[$_]) for 0..$#_;
+  $s==$_[$_] ? (return $_) : ($s-=2*$_[$_]) for 0..$#_;
+  -1;
+}
+
+## Optimized solution for +ve values only....
+
+sub equilibrium_index_positive {
+  my $s = 0;
+  $s += $_ for @_;
+  $s==$_[$_] ? (return $_) : $s<$_[$_] ? (return -1) : ($s-=2*$_[$_]) for 0..$#_;
   -1;
 }