1 ! Copyright (c) 2007 Samuel Tardieu, Aaron Schaefer.
2 ! See http://factorcode.org/license.txt for BSD license.
3 USING: io.files math.parser namespaces project-euler.common sequences splitting ;
6 ! http://projecteuler.net/index.php?section=problems&id=67
11 ! By starting at the top of the triangle below and moving to adjacent numbers
12 ! on the row below, the maximum total from top to bottom is 23.
19 ! That is, 3 + 7 + 4 + 9 = 23.
21 ! Find the maximum total from top to bottom in triangle.txt (right click and
22 ! 'Save Link/Target As...'), a 15K text file containing a triangle with
25 ! NOTE: This is a much more difficult version of Problem 18. It is not possible
26 ! to try every route to solve this problem, as there are 2^99 altogether! If you
27 ! could check one trillion (10^12) routes every second it would take over twenty
28 ! billion years to check them all. There is an efficient algorithm to solve it. ;o)
34 ! Propagate from bottom to top the longest cumulative path as is done in
39 : source-067 ( -- seq )
40 "extra/project-euler/067/triangle.txt" resource-path
41 file-lines [ " " split [ string>number ] map ] map ;
45 : euler067 ( -- answer )
46 source-067 propagate-all first first ;
48 ! [ euler067 ] 100 ave-time
49 ! 18 ms run / 0 ms GC time
55 : euler067a ( -- answer )
58 ! [ euler067a ] 100 ave-time
59 ! 14 ms run / 0 ms GC ave time - 100 trials
61 ! source-067 [ max-path ] curry 100 ave-time
62 ! 3 ms run / 0 ms GC ave time - 100 trials