add "1-liner" solution & display fn

1 files changed, 52 insertions, 3 deletions

diff --git a/challenge-100/james-smith/perl/ch-2.pl b/challenge-100/james-smith/perl/ch-2.pl
index 0b00be3ba6..f46b12cf6f 100644
--- a/challenge-100/james-smith/perl/ch-2.pl
+++ b/challenge-100/james-smith/perl/ch-2.pl
@@ -6,11 +6,24 @@ use warnings;
 use feature qw(say);
 use Test::More;
 
-is( triangle_sum( [1],[2,4],[6,4,9],[5,1,7,2] ), 8 );
-is( triangle_sum( [3],[3,1],[5,2,3],[4,3,1,3] ), 7 );
+is( triangle_sum( [1],[2,4],[6,4,9],[5,1,7,2] ),  8 );
+is( triangle_sum( [3],[3,1],[5,2,3],[4,3,1,3] ),  7 );
+is( triangle_sum( [2],[3,7],[8,5,6],[6,1,9,3] ), 11 );
+is( triangle_sum( [3],[6,4],[5,2,7],[9,1,8,6] ), 10 );
+
+is( triangle_sum_1point5_liner( [1],[2,4],[6,4,9],[5,1,7,2] ),  8 );
+is( triangle_sum_1point5_liner( [3],[3,1],[5,2,3],[4,3,1,3] ),  7 );
+is( triangle_sum_1point5_liner( [2],[3,7],[8,5,6],[6,1,9,3] ), 11 );
+is( triangle_sum_1point5_liner( [3],[6,4],[5,2,7],[9,1,8,6] ), 10 );
 
 done_testing();
 
+display_sum( [1],[2,4],[6,4,9],[5,1,7,2] );
+display_sum( [3],[3,1],[5,2,3],[4,3,1,3] );
+display_sum( [2],[3,7],[8,5,6],[6,1,9,3] );
+display_sum( [3],[6,4],[5,2,7],[9,1,8,6] );
+
+
 ## 72 chars ############################################################
 
 ## There are two directions you can go with this problem (up or down)
@@ -26,8 +39,44 @@ sub triangle_sum {
       ## Strip off base of triangle...
     my $b = pop @tri;
       ## Update new last line by adding smallest of it's "children"
-    $tri[-1][$_] += $b->[$b->[$_]<$b->[$_+1]?$_:$_+1] for 0..@tri-1;
+    $tri[-1][$_] += $b->[
+      $b->[$_] < $b->[$_+1] ? $_ : $_+1
+    ] for 0..@tri-1;
   }
   return $tri[0][0];
 }
 
+## We can convert the inner for loop into a map... and pop the value
+## of $b in the while clause so we can simplify this down to a single
+## one line statement, with the return just returning the last
+## element of $b - here we are using the implicit my $b & return
+##
+## so not quite a 1 liner - but close enough!!
+
+sub triangle_sum_1point5_liner {
+  @{$_[-1]} = map {
+    $_[-1][$_] + $b->[ $b->[$_] < $b->[$_+1] ? $_ : $_+1 ]
+  } 0..@_-1 while @{$b=pop @_}>1;
+  $b->[0];
+}
+
+sub display_sum {
+  my @tri = @_;
+  my @route;
+  while(@{$b = pop @tri}>1) {
+    ($tri[-1][$_],$route[$_]) = $b->[$_]<$b->[$_+1]
+      ? ( $tri[-1][$_] + $b->[$_],   [$_,  @{$route[$_  ]||[]}] )
+      : ( $tri[-1][$_] + $b->[$_+1], [$_+1,@{$route[$_+1]||[]}] ) foreach 0..@tri-1;
+  }
+  @route = (0,@{$route[0]});
+  print
+    '',
+    ( map {
+      '  ' x (@_-($a=$_)),
+      ( map {
+        sprintf $route[$a]==$_ ? '[%d] ': ' %d  ' , $_[$a][$_]
+      } 0..$a ),
+      "\n"
+    } 0..@_-1 ),
+    "\n";
+}