2019: Day 5 Part 1

2019/day5/intcode.rb

@@ -2,34 +2,70 @@
 
 module Intcode
   def self.read(filename)
-    Program.new File.read(filename).split(',').map(&:to_i)
+    input = File.read(filename)
+                .gsub(/^#.*$/, '')
+                .gsub('\s', '')
+    Program.new(parse(input))
+  end
+
+  def self.parse(input)
+    input.split(',').map(&:to_i)
   end
 
   class Program
-    attr_reader :mem
+    attr_accessor :mem
     def initialize(mem)
-      @mem = mem
+      @mem = mem.clone
+
+      def @mem.to_s
+        batch_size = 10
+        output = String.new
+        each_slice(batch_size).each_with_index do |batch, idx|
+          prefix = idx * batch_size
+          output << "#{prefix}: #{batch.join(' ')}\n"
+        end
+        output
+      end
     end
 
-    def run(noun, verb)
-      mem = @mem.clone
-      mem[1] = noun
-      mem[2] = verb
+    def run
       pc = 0
       loop do
-        case mem[pc]
+        opcode = operation(mem[pc])
+        mode = modes(mem[pc])
+        case opcode
         when 1
           r1 = mem[pc + 1]
           r2 = mem[pc + 2]
           r3 = mem[pc + 3]
-          mem[r3] = mem[r1] + mem[r2]
+          a = param(r1, mode[0])
+          b = param(r2, mode[1])
+          raise StandardError, "unexpected mode: #{mode[2]}" if mode[2] != 0
+
+          mem[r3] = a + b
           pc += 4
         when 2
           r1 = mem[pc + 1]
           r2 = mem[pc + 2]
           r3 = mem[pc + 3]
-          mem[r3] = mem[r1] * mem[r2]
+          a = param(r1, mode[0])
+          b = param(r2, mode[1])
+          raise StandardError, "unexpected mode: #{mode[2]}" if mode[2] != 0
+
+          mem[r3] = a * b
           pc += 4
+        when 3
+          r1 = mem[pc + 1]
+          raise StandardError, "unexpected mode: #{mode[0]}" if mode[0] != 0
+
+          mem[r1] = input
+          pc += 2
+        when 4
+          r1 = mem[pc + 1]
+          output = param(r1, mode[0])
+          puts "output: #{output}"
+
+          pc += 2
         when 99
           return mem[0]
         else
@@ -37,5 +73,35 @@ module Intcode
         end
       end
     end
+
+    private
+
+    def input
+      print 'input> '
+      gets.to_i
+    end
+
+    def operation(cell)
+      (cell % 100)
+    end
+
+    def modes(cell)
+      m = Hash.new(0)
+      (cell / 100).truncate.digits.each_with_index do |d, i|
+        m[i] = d
+      end
+      m
+    end
+
+    def param(val, mode)
+      case mode
+      when 0
+        mem[val]
+      when 1
+        val
+      else
+        raise StandardError, "unexpected mode: #{mode}"
+      end
+    end
   end
 end