day6.cr

@@ -2,12 +2,20 @@ require "advent"
 INPUT = input(2020, 6).split("\n\n")
 
 def part1
-  INPUT.sum &.chars.uniq!.count(&.ascii_letter?)
+  input = INPUT.clone
+  answers = input.map do |i|
+    i.chars.uniq!.count &.ascii_letter?
+  end
+  puts answers.sum
 end
 
 def part2
-  INPUT.sum &.lines.map(&.chars.to_set).intersect.size
+  input = INPUT.clone
+  sol = input.map do |i|
+    i.split("\n").reject(&.empty?).map(&.chars.to_set).reduce { |s1, s2| s1 & s2 }
+  end
+  puts(sol.map(&.size).sum)
 end
 
-puts part1
+part1
-puts part2
+part2

day7.cr

@@ -1,45 +0,0 @@
-require "advent"
-
-INPUT = input(2020, 7).lines.map(&.chomp).map do |s|
-  data = s.match(/^([a-z ]+) bags contain (.*).$/).not_nil!
-  contents = data[2].split(", ").compact_map do |s|
-    s.match(/(\d+) (.*) bags?/).try { |m| {m[1].to_i32, m[2]} }
-  end
-  {data[1], contents}
-end
-
-def build_graph(input)
-  gr = Graph(String).new
-  seen = Set(String).new
-  input.each do |i|
-    seen << i[0]
-    i[1].each do |to|
-      n, m = to
-      gr.add_edge(i[0], m, n)
-    end
-  end
-  {seen, gr}
-end
-
-def part1
-  seen, gr = build_graph(INPUT)
-  seen.count do |s|
-    gr.find_path(s, "shiny gold") && s != "shiny gold"
-  end
-end
-
-def count_bags(gr, current)
-  return 1 unless es = gr.@edges[current]?
-  1 + es.sum do |e|
-    t, k = e
-    k * count_bags(gr, t)
-  end
-end
-
-def part2
-  seen, gr = build_graph(INPUT)
-  count_bags(gr, "shiny gold") - 1
-end
-
-puts part1
-puts part2

day8.cr

@@ -1,44 +0,0 @@
-require "advent"
-INPUT = input(2020, 8).lines.map do |s|
-  code, int = s.split(" ")
-  {code, int.to_i32}
-end
-
-def run(prog)
-  acc = 0
-  pc = 0
-  visited = Set(Int32).new
-  loop do
-    return {:term, acc} if pc >= prog.size
-    return {:inf, acc} if visited.includes? pc
-      
-    visited << pc
-    code, int = prog[pc]
-    case code
-    when "acc"
-      acc += int
-    when "jmp"
-      pc += int - 1
-    end
-    pc += 1
-  end
-end
-
-def part1
-  run(INPUT)[1]
-end
-
-def part2
-  jnp = INPUT.find_indices { |e| e[0] == "jmp" || e[0] == "nop" }
-  jnp.each do |i|
-    prog = INPUT.clone
-    op, int = prog[i]
-    prog[i] = {op.tr("jmpnop", "nopjmp"), int}
-
-    code, acc = run(prog)
-    return acc if code == :term
-  end
-end
-
-puts part1
-puts part2