using newtons method - but written compactly

1 files changed, 4 insertions, 16 deletions

diff --git a/challenge-133/james-smith/perl/ch-1.pl b/challenge-133/james-smith/perl/ch-1.pl
index 5a342656e6..9422daa9e4 100644
--- a/challenge-133/james-smith/perl/ch-1.pl
+++ b/challenge-133/james-smith/perl/ch-1.pl
@@ -5,8 +5,6 @@ use strict;
 use warnings;
 use feature qw(say);
 use Test::More;
-use Benchmark qw(cmpthese timethis);
-use Data::Dumper qw(Dumper);
 
 my @TESTS = (
   [ 10, 3 ],
@@ -21,19 +19,9 @@ is( find_root($_->[0]), $_->[1] ) foreach @TESTS;
 done_testing();
 
 sub find_root {
-  my $n = shift;
-  ## Make order of magnitude guess
-  my ($l,$r) = (1 & length $n ) ? (       10 ** int(0.5*length $n),  3.2 * 10 ** int(0.5*length $n) )
-                                : ( 0.3 * 10 ** int(0.5*length $n),        10 ** int(0.5*length $n) );
-  while($r - $l > 1) {
-    print "+";
-    my $m = $l + int(( $r-$l)/2);
-    if( $m*$m < $n ) {
-      $l=$m;
-    } else {
-      $r=$m;
-    }
-  }
-  return $l;
+  my($x,$y) = (my $n = shift)>>1;
+  return $n unless $x;
+  $x = $y while ($y = ($x+$n/$x)>>1) < $x;
+  return $x;
 }