! http://projecteuler.net/index.php?section=problems&id=18 ! problem18.factor ! wookay.noh at gmail.com USING: splitting math math.parser sequences kernel arrays ascii prettyprint ; IN: problem18 : duex_at ( seq pos -- x y ) dup 2 + rot subseq first2 ; : bigger ( pos x y -- val pos ) 2dup > [ drop ] [ nip [ 1 + ] dip ] if swap ; : trian ( seq pos seq -- seq pos ) dup length 1 = [ first swap ] [ 2dup drop duex_at bigger ] if -rot suffix swap ; : route ( seq -- result ) { } 0 rot [ first " " split [ string>number ] map trian ] each drop sum ; : split-lines ( seq -- data ) [ blank? ] trim "\n" split [ { } swap suffix ] map ; """ 3 7 4 2 4 6 8 5 9 3 """ split-lines route . """ 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 """ split-lines route . USE: simple-flat-file "triangle.txt" data route .