Done puzzle 39
[project-euler.git] / euler18.rb
1 require 'logger'
2
3 $triangle_source = <<TRIANGLE
4 75
5 95 64
6 17 47 82
7 18 35 87 10
8 20 04 82 47 65
9 19 01 23 75 03 34
10 88 02 77 73 07 63 67
11 99 65 04 28 06 16 70 92
12 41 41 26 56 83 40 80 70 33
13 41 48 72 33 47 32 37 16 94 29
14 53 71 44 65 25 43 91 52 97 51 14
15 70 11 33 28 77 73 17 78 39 68 17 57
16 91 71 52 38 17 14 91 43 58 50 27 29 48
17 63 66 04 68 89 53 67 30 73 16 69 87 40 31
18 04 62 98 27 23 09 70 98 73 93 38 53 60 04 23
19 TRIANGLE
20
21 $triangle = $triangle_source.split("\n").map {|line| line.split.map {|s| s.to_i}}
22
23 def find_best(triangle)
24 log = Logger.new(STDERR)
25 log.level = Logger::WARN
26 last_line_totals = [0]
27 this_line_totals = []
28 triangle.each do |line|
29 log.info {"Checking line #{line}"}
30 this_line_totals = []
31 line.each_index do |i|
32 this_line_totals << [i == 0 ? 0 : last_line_totals[i-1] + line[i],
33 i == last_line_totals.length ? 0 : last_line_totals[i] + line[i]].max
34 end
35 log.info {"Best totals for line #{line} are #{this_line_totals}"}
36 last_line_totals = this_line_totals
37 end
38 log.close
39 this_line_totals.max
40 end
41
42 if __FILE__==$0
43 puts find_best $triangle
44 end