Day 8

2023/day8/p1.rb

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+# frozen_string_literal: true
+
+f = File.open('./2023/day8/data')
+directions = f.readline.strip.split('')
+
+graph = {}
+f.each_line do |line|
+  line.strip!
+  next if line.empty?
+
+  graph[line.split(' ')[0]] = line.split('(')[1].split(')')[0].split(', ')
+end
+
+i = 0
+res = 0
+cur_pos = 'AAA'
+while cur_pos != 'ZZZ'
+  i = 0 if i == directions.length
+
+  cur_pos = graph[cur_pos][0] if directions[i] == 'L'
+  cur_pos = graph[cur_pos][1] if directions[i] == 'R'
+  i += 1
+  res += 1
+end
+
+puts res

2023/day8/p2.rb

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+# frozen_string_literal: true
+
+f = File.open('./2023/day8/data')
+directions = f.readline.strip.split('')
+
+starting_vertices = []
+graph = {}
+f.each_line do |line|
+  line.strip!
+  next if line.empty?
+
+  vertex_label = line.split(' ')[0]
+  graph[vertex_label] = line.split('(')[1].split(')')[0].split(', ')
+  starting_vertices << vertex_label if vertex_label.end_with? 'A'
+end
+
+res = -1
+starting_vertices.each do |vertex|
+  i = 0
+  curr_length = 0
+  cur_pos = vertex
+  until cur_pos.end_with? 'Z'
+    i = 0 if i == directions.length
+
+    cur_pos = graph[cur_pos][0] if directions[i] == 'L'
+    cur_pos = graph[cur_pos][1] if directions[i] == 'R'
+    i += 1
+    curr_length += 1
+  end
+  res = if res == -1
+          curr_length
+        else
+          res.lcm(curr_length)
+        end
+end
+
+puts res