Mercurial > repos > other > adventofcode2023
view day2b.rb @ 39:0e17e4bd97a9 default tip
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 | 49dd1ae93696 |
children |
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#! /usr/bin/env ruby if ARGV.length != 1 abort("Incorrect arguments - needs input file") elsif not File.exist? (ARGV[0]) abort("File #{ARGV[0]} did not exist") end file = ARGV[0] sum = 0 File.open(file, "r").each_line do |line| _, all_picks = line.split(":") sum += all_picks.split(";").map do |pick| pick.split(",").to_h { |colour_pick| colour_pick.strip.split(" ").reverse }.transform_values(&:to_i) end.reduce(Hash.new) {|reduced,obj| reduced.merge(obj) { |key,val1,val2| val1 > val2 ? val1 : val2 }}.values.reduce(1, :*) end puts sum