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annotate day15.rb @ 39:0e17e4bd97a9 default tip

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Rewrite as four-dimensional route finding The grid isn't just a 2D grid. The constraints make it 4D: * X * Y * Last direction * Number of steps in that direction By tracking all four dimensions, we can find the shortest route for _all_ combinations of the constraint. Previously, we were dropping routes that were currently longer but ended up shorter because they could take subsequent steps that other routes couldn't.
author IBBoard <dev@ibboard.co.uk>
date Sun, 22 Sep 2024 11:30:53 +0100
parents ad73a2ff3d06
children
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
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22
ad73a2ff3d06 Implement Day 15 part 1 and all of Day 16
IBBoard <dev@ibboard.co.uk>
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1 #! /usr/bin/env ruby
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2
ad73a2ff3d06 Implement Day 15 part 1 and all of Day 16
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3 if ARGV.length != 1
ad73a2ff3d06 Implement Day 15 part 1 and all of Day 16
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4 abort("Incorrect arguments - needs input file")
ad73a2ff3d06 Implement Day 15 part 1 and all of Day 16
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5 elsif not File.exist? (ARGV[0])
ad73a2ff3d06 Implement Day 15 part 1 and all of Day 16
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6 abort("File #{ARGV[0]} did not exist")
ad73a2ff3d06 Implement Day 15 part 1 and all of Day 16
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7 end
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8
ad73a2ff3d06 Implement Day 15 part 1 and all of Day 16
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9 file = ARGV[0]
ad73a2ff3d06 Implement Day 15 part 1 and all of Day 16
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10
ad73a2ff3d06 Implement Day 15 part 1 and all of Day 16
IBBoard <dev@ibboard.co.uk>
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11 puts File.open(file, "r").each_line(chomp: true).first.split(",").map {|str| str.each_char.map(&:ord).reduce(0) {|sum, c| puts ((sum + c) * 17) % 256; ((sum + c) * 17) % 256 }}.reduce(:+)