Re^4: Brute force vs algorithm (PWC # 100)

Here, my take on this,(a variation from that solution)

Our approaches are not that different, your dynamic "cache" is just my explicit "weight" triangle.

And you are needing more resources for recursion and hash.

But you could improve it by adding bound criteria (i.e. no need to calculate a subtree if it has no chance to be better than the current minimum).

Though I'm not sure this will pay of, my algorithm is already O(m) with m #cells.

Cheers Rolf
_{(addicted to the Perl Programming Language :)

Wikisyntax for the Monastery}

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Re^5: Brute force vs algorithm (PWC # 100) by tybalt89 (Monsignor) on Feb 16, 2021 at 04:39 UTC
For people who don't like recursion and hashes :) `#!/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";` [download]	[reply] [d/l]
Re^6: Brute force vs algorithm (PWC # 100) by tybalt89 (Monsignor) on Feb 16, 2021 at 05:04 UTC
Or for a big mess, compute the score and the path simultaneously :) #!/usr/bin/perl use strict; # https://perlmonks.org/?node_id=11128406 use warnings; use List::Util qw( reduce min ); local $_ = <<END; 1 2 4 6 4 9 5 1 7 2 END my @d = map [ split ], split /\n/; $d[$#d][$_] = [ $d[$#d][$_], $d[$#d][$_] ] for 0 .. $#d; for my $r ( reverse 0 .. $#d - 1 ) { for my $c ( 0 .. $r ) { $d[$r][$c] = [ $d[$r][$c] + min( $d[$r+1][$c][0], $d[$r+1][$c+1][0 +]), "$d[$r][$c] + " . (reduce { $a->[0] <= $b->[0] ? $a : $b } $d[$r+1][$c], $d[$r+1][$c+1])->[1] ]; } } print "value $d[0][0][0] path $d[0][0][1]\n"; [download] Outputs: `value 8 path 1 + 2 + 4 + 1` [download]	[reply] [d/l] [select]


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