#!/usr/bin/perl

use strict; # https://perlmonks.org/?node_id=11128406
use warnings;
use List::Util qw( reduce );

local $_ = <<END;
            1
           2 4
          6 4 9
         5 1 7 2
END
my @d = map [ split ], split /\n/;

for my $r ( reverse 0 .. $#d - 1 )
  {
  for my $c ( 0 .. $r )
    {
    $d[$r][$c] .= ' + ' . reduce { eval $a <= eval $b ? $a : $b }
      $d[$r+1][$c], $d[$r+1][$c+1];
    }
  }

print "$d[0][0]\n";