From f37c40b2ea0471760c12f04951f5f8ee54af6bc7 Mon Sep 17 00:00:00 2001
From: Jesse Luehrs <doy@tozt.net>
Date: Thu, 14 May 2009 21:30:56 -0500
Subject: solution to number 18

---
 018.pl | 44 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)
 create mode 100755 018.pl

diff --git a/018.pl b/018.pl
new file mode 100755
index 0000000..6a9ec1c
--- /dev/null
+++ b/018.pl
@@ -0,0 +1,44 @@
+#!/usr/bin/perl
+use strict;
+use warnings;
+# http://tozt.net/code/Graph-Implicit/
+use Graph::Implicit;
+use List::Util qw/sum max/;
+
+my $triangle_txt = <<'TRIANGLE';
+                     75
+                   95 64
+                  17 47 82
+                18 35 87 10
+               20 04 82 47 65
+             19 01 23 75 03 34
+            88 02 77 73 07 63 67
+          99 65 04 28 06 16 70 92
+         41 41 26 56 83 40 80 70 33
+       41 48 72 33 47 32 37 16 94 29
+      53 71 44 65 25 43 91 52 97 51 14
+    70 11 33 28 77 73 17 78 39 68 17 57
+   91 71 52 38 17 14 91 43 58 50 27 29 48
+ 63 66 04 68 89 53 67 30 73 16 69 87 40 31
+04 62 98 27 23 09 70 98 73 93 38 53 60 04 23
+TRIANGLE
+my @triangle_lines = split /\n/, $triangle_txt;
+my @triangle = map { [split ' ', $_] } @triangle_lines;
+use DDS;
+
+my $graph = Graph::Implicit->new(sub {
+    my ($vx, $vy) = split ' ', shift;
+    return if $vx == @triangle - 1;
+    #print "$vx, $vy -> ", $vx + 1, ", $vy and ", $vx + 1, ", ", $vy + 1, "\n";
+    return ([($vx + 1) . " " . $vy,       100 - $triangle[$vx + 1][$vy]],
+            [($vx + 1) . " " . ($vy + 1), 100 - $triangle[$vx + 1][$vy + 1]]);
+});
+my ($paths, $blah) = $graph->dijkstra("0 0");
+my @paths;
+for my $i (0..14) {
+    push @paths, [Graph::Implicit::make_path($paths, "14 $i")];
+}
+my @path_values = map { [map { my ($x, $y) = split; $triangle[$x][$y] } @$_] }
+                      @paths;
+my @path_sums = map { sum @$_ } @path_values;
+print max(@path_sums), "\n";
-- 
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