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From: Melzzzzz <mel@zzzzz.com>
Newsgroups: comp.lang.forth
Subject: Re: Project Euler 18.
Date: Thu, 12 Jan 2017 11:14:06 +0100
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On Thu, 12 Jan 2017 06:21:39 +0000 (UTC)
"Robert L." <No_spamming@noWhere_7073.org> wrote:

> Find the maximum total from top to bottom of the triangle below:
> 
> Ruby:
> 
> 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".
>   each_line.map{|line| line.scan( /\d+/ ).map &:to_i}
> 
> $max_total = 0
> def maximize( sum, column, delta, (row,*rest) )
>   if !row
>     $max_total = [$max_total, sum].max
>   else
>     column.upto(column + delta){|i| maximize(sum + row[i], i, 1,
> rest)} end
> end
> maximize(0,0,0,triangle)
> $max_total
> 
>  ===>  
> 1074
> 
> In Forth?
> 
> 

https://projecteuler.net/problem=67
NOTE: This is a much more difficult version of Problem 18. It is not
possible to try every route to solve this problem, as there are 299
altogether! If you could check one trillion (1012) routes every second
it would take over twenty billion years to check them all. There is an
efficient algorithm to solve it. ;o)

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