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annotate day6.rb @ 6:9d89489bc939

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Day 6 part 1 - calculate times above range
author IBBoard <dev@ibboard.co.uk>
date Thu, 07 Dec 2023 08:16:30 +0000
parents
children 51e5f26dc81e
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6
9d89489bc939 Day 6 part 1 - calculate times above range
IBBoard <dev@ibboard.co.uk>
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1 #! /usr/bin/env ruby
9d89489bc939 Day 6 part 1 - calculate times above range
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2
9d89489bc939 Day 6 part 1 - calculate times above range
IBBoard <dev@ibboard.co.uk>
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3 if ARGV.length != 1
9d89489bc939 Day 6 part 1 - calculate times above range
IBBoard <dev@ibboard.co.uk>
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4 abort("Incorrect arguments - needs input file")
9d89489bc939 Day 6 part 1 - calculate times above range
IBBoard <dev@ibboard.co.uk>
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5 elsif not File.exist? (ARGV[0])
9d89489bc939 Day 6 part 1 - calculate times above range
IBBoard <dev@ibboard.co.uk>
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6 abort("File #{ARGV[0]} did not exist")
9d89489bc939 Day 6 part 1 - calculate times above range
IBBoard <dev@ibboard.co.uk>
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7 end
9d89489bc939 Day 6 part 1 - calculate times above range
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8
9d89489bc939 Day 6 part 1 - calculate times above range
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9 file = ARGV[0]
9d89489bc939 Day 6 part 1 - calculate times above range
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10
9d89489bc939 Day 6 part 1 - calculate times above range
IBBoard <dev@ibboard.co.uk>
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11 times, distances = File.open(file, "r").each_line(chomp: true).map {|v| v.split(":")[1].split(" ").map(&:to_i)}
9d89489bc939 Day 6 part 1 - calculate times above range
IBBoard <dev@ibboard.co.uk>
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12 events = times.zip(distances)
9d89489bc939 Day 6 part 1 - calculate times above range
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13
9d89489bc939 Day 6 part 1 - calculate times above range
IBBoard <dev@ibboard.co.uk>
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14 product = events.map do |event|
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15 mid = (event[0].to_f / 2).floor
9d89489bc939 Day 6 part 1 - calculate times above range
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16 first_success = (1..mid).bsearch {|i| (event[0] - i) * i > event[1]}
9d89489bc939 Day 6 part 1 - calculate times above range
IBBoard <dev@ibboard.co.uk>
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17 num_success = (mid - first_success + 1) * 2
9d89489bc939 Day 6 part 1 - calculate times above range
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18 event[0].odd? ? num_success : num_success - 1
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19 end.reduce(:*)
9d89489bc939 Day 6 part 1 - calculate times above range
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20
9d89489bc939 Day 6 part 1 - calculate times above range
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21 puts product