2019: Day 2 (ruby prototype)

Author: emptyflask

2019/day02.rb

@@ -0,0 +1,40 @@
+input = File.read("./02/input.txt").chomp.split(',').map(&:to_i)
+
+def cpu(mem, pos)
+  case mem[pos]
+  when 1
+    # add
+    mem[mem[pos+3]] = mem[mem[pos+1]] + mem[mem[pos+2]]
+  when 2
+    # mult
+    mem[mem[pos+3]] = mem[mem[pos+1]] * mem[mem[pos+2]]
+  when 99
+    # halt and output
+    return mem[0]
+  end
+  # run next instruction
+  cpu(mem, pos+4)
+end
+
+def solve1(input)
+  input.dup.then do |mem|
+    mem[1] = 12
+    mem[2] = 2
+    cpu(mem, 0)
+  end
+end
+
+def solve2(input)
+  noun, verb = (0..99).to_a.combination(2).detect do |test|
+    19690720 == input.dup.then do |mem|
+      mem[1] = test[0]
+      mem[2] = test[1]
+      cpu(mem, 0)
+    end
+  end
+
+  100 * noun + verb
+end
+
+puts "Part 1: #{ solve1(input) }"
+puts "Part 2: #{ solve2(input) }"