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annotate day6.rb @ 33:676461cc3a70

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Day 23 - track segments, not each space This allows us to explore the branches once then do quicker calculations for valid route lengths. But still requires exploring 1,262,816 routes to find the longest!
author IBBoard <dev@ibboard.co.uk>
date Thu, 04 Jan 2024 14:52:24 +0000
parents 51e5f26dc81e
children
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
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9d89489bc939 Day 6 part 1 - calculate times above range
IBBoard <dev@ibboard.co.uk>
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1 #! /usr/bin/env ruby
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2
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3 if ARGV.length != 1
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4 abort("Incorrect arguments - needs input file")
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5 elsif not File.exist? (ARGV[0])
9d89489bc939 Day 6 part 1 - calculate times above range
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6 abort("File #{ARGV[0]} did not exist")
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7 end
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9 file = ARGV[0]
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51e5f26dc81e Add a template file for reuse
IBBoard <dev@ibboard.co.uk>
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11 times, distances = File.open(file, "r").each_line(chomp: true).map {|v| puts v; puts v.split(":"); v.split(":")[1].split(" ").map(&:to_i)}
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9d89489bc939 Day 6 part 1 - calculate times above range
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12 events = times.zip(distances)
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14 product = events.map do |event|
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15 mid = (event[0].to_f / 2).floor
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16 first_success = (1..mid).bsearch {|i| (event[0] - i) * i > event[1]}
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17 num_success = (mid - first_success + 1) * 2
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18 event[0].odd? ? num_success : num_success - 1
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19 end.reduce(:*)
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20
9d89489bc939 Day 6 part 1 - calculate times above range
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21 puts product