Mercurial > repos > other > adventofcode2023
view day17.rb @ 25:79dc2ba41df2
Copy a Dijkstra's Algorithm implementation
Gets us the shorted route but doesn't handle the additional
"keep turning" conditions
author | IBBoard <dev@ibboard.co.uk> |
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date | Sun, 17 Dec 2023 10:32:05 +0000 |
parents | |
children | eb6c3a7d2f72 |
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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] Coord = Struct.new(:x, :y) city_map = File.open(file, "r").each_line(chomp: true).map{ |line| line.each_char.map(&:to_i)} distances = Array.new(city_map.length) {Array.new(city_map[0].length) {Float::INFINITY}} distances[0][0] = 0 visited = Array.new(city_map.length) {Array.new(city_map[0].length)} unvisited = [] (0...city_map.length).each {|y| (0...city_map[0].length).each {|x| unvisited << Coord.new(x,y)}} def get_neighbours(city_map, x, y) [Coord.new(-1,0), Coord.new(1,0), Coord.new(0,-1), Coord.new(0,1)].map {|coord| Coord.new(coord.x + x, coord.y + y)}.filter {|coord| coord.x >= 0 and coord.y >= 0 and coord.x < city_map[0].length and coord.y < city_map.length} end until unvisited.empty? min_node = nil unvisited.each do |node| if min_node.nil? || distances[node.y][node.x] < distances[min_node.y][min_node.x] min_node = node unless visited[node.y][node.x] end end break if distances[min_node.y][min_node.x] == Float::INFINITY cur_distance = distances[min_node.y][min_node.x] get_neighbours(city_map, min_node.x, min_node.y).each do |neighbour| value = city_map[neighbour.y][neighbour.x] alt = cur_distance + value distances[neighbour.y][neighbour.x] = alt if alt < distances[neighbour.y][neighbour.x] end visited[min_node.y][min_node.x] = true unvisited.delete(min_node) distances end puts distances[-1][-1]