From 2daf9159b43c229f9ea7aa13c9279c0670d077c9 Mon Sep 17 00:00:00 2001
From: Jeremy Kaplan <jdkaplan@metagram.net>
Date: Sun, 8 Dec 2019 21:16:04 -0800
Subject: [PATCH] 2019: Day 7 Part 1

---
 2019/day7/input      |   1 +
 2019/day7/intcode.rb | 223 +++++++++++++++++++++++++++++++++++++++++++
 2019/day7/part1.rb   |  61 ++++++++++++
 3 files changed, 285 insertions(+)
 create mode 100644 2019/day7/input
 create mode 100644 2019/day7/intcode.rb
 create mode 100644 2019/day7/part1.rb

diff --git a/2019/day7/input b/2019/day7/input
new file mode 100644
index 0000000..b7f4dc4
--- /dev/null
+++ b/2019/day7/input
@@ -0,0 +1 @@
+3,8,1001,8,10,8,105,1,0,0,21,34,55,68,93,106,187,268,349,430,99999,3,9,102,5,9,9,1001,9,2,9,4,9,99,3,9,1001,9,5,9,102,2,9,9,101,2,9,9,102,2,9,9,4,9,99,3,9,101,2,9,9,102,4,9,9,4,9,99,3,9,101,4,9,9,102,3,9,9,1001,9,2,9,102,4,9,9,1001,9,2,9,4,9,99,3,9,101,2,9,9,1002,9,5,9,4,9,99,3,9,101,1,9,9,4,9,3,9,1002,9,2,9,4,9,3,9,1002,9,2,9,4,9,3,9,1002,9,2,9,4,9,3,9,101,2,9,9,4,9,3,9,1001,9,2,9,4,9,3,9,1002,9,2,9,4,9,3,9,102,2,9,9,4,9,3,9,1002,9,2,9,4,9,3,9,101,1,9,9,4,9,99,3,9,101,2,9,9,4,9,3,9,1001,9,1,9,4,9,3,9,101,1,9,9,4,9,3,9,1001,9,1,9,4,9,3,9,1001,9,2,9,4,9,3,9,102,2,9,9,4,9,3,9,1001,9,1,9,4,9,3,9,102,2,9,9,4,9,3,9,1001,9,1,9,4,9,3,9,101,2,9,9,4,9,99,3,9,102,2,9,9,4,9,3,9,102,2,9,9,4,9,3,9,1002,9,2,9,4,9,3,9,1002,9,2,9,4,9,3,9,1002,9,2,9,4,9,3,9,101,1,9,9,4,9,3,9,101,1,9,9,4,9,3,9,101,1,9,9,4,9,3,9,101,2,9,9,4,9,3,9,1001,9,2,9,4,9,99,3,9,1002,9,2,9,4,9,3,9,1002,9,2,9,4,9,3,9,1001,9,2,9,4,9,3,9,1002,9,2,9,4,9,3,9,1002,9,2,9,4,9,3,9,101,2,9,9,4,9,3,9,1001,9,2,9,4,9,3,9,101,1,9,9,4,9,3,9,101,1,9,9,4,9,3,9,101,1,9,9,4,9,99,3,9,101,2,9,9,4,9,3,9,1002,9,2,9,4,9,3,9,1002,9,2,9,4,9,3,9,101,1,9,9,4,9,3,9,1001,9,1,9,4,9,3,9,101,2,9,9,4,9,3,9,1002,9,2,9,4,9,3,9,1002,9,2,9,4,9,3,9,1002,9,2,9,4,9,3,9,1002,9,2,9,4,9,99
diff --git a/2019/day7/intcode.rb b/2019/day7/intcode.rb
new file mode 100644
index 0000000..c0fd23e
--- /dev/null
+++ b/2019/day7/intcode.rb
@@ -0,0 +1,223 @@
+# frozen_string_literal: true
+
+require 'forwardable'
+
+module Intcode
+  def self.read(filename)
+    parse File.read(filename)
+  end
+
+  def self.parse(input)
+    parsed = input
+             .gsub(/^#.*$/, '')
+             .gsub('\s', '')
+             .split(',')
+             .map(&:to_i)
+    Program.new parsed
+  end
+
+  class Program
+    def initialize(mem)
+      @initial_state = mem
+    end
+
+    def as_memory
+      Memory.new(@initial_state.clone)
+    end
+
+    def run(&user_input)
+      Computer.new(as_memory).run(&user_input)
+    end
+  end
+
+  class Memory
+    extend Forwardable
+
+    def_delegator :@cells, :[]
+    def_delegator :@cells, :[]=
+
+    def initialize(cells)
+      @cells = cells
+    end
+
+    def to_s
+      batch_size = 10
+      s = String.new
+      @cells.each_slice(batch_size).each_with_index do |batch, idx|
+        prefix = idx * batch_size
+        s << "#{prefix}: #{batch.join(' ')}\n"
+      end
+      s
+    end
+
+    def [](idx)
+      raise ArgumentError, "index out of range: #{idx}" if idx.negative? || idx >= @cells.length
+
+      @cells[idx]
+    end
+
+    def []=(idx, val)
+      raise ArgumentError, "index out of range: #{idx}" if idx.negative? || idx >= @cells.length
+
+      @cells[idx] = val
+    end
+  end
+
+  class Computer
+    def initialize(mem, &block)
+      @mem = mem
+      @ip = 0
+      @input_block = block
+    end
+
+    def on_output(&block)
+      @output_block = block
+    end
+
+    def run
+      loop do
+        return if tick == :done_executing
+      end
+    end
+
+    def tick
+      case operation(@mem[@ip])
+      when 1
+        add!
+      when 2
+        mul!
+      when 3
+        input!(&@input_block)
+      when 4
+        output!(&@output_block)
+      when 5
+        branch_if_not_zero!
+      when 6
+        branch_if_zero!
+      when 7
+        less_than!
+      when 8
+        equal!
+      when 99
+        :done_executing
+      else
+        raise StandardError, "unexpected opcode: #{opcode}"
+      end
+    end
+
+    private
+
+    def add!
+      mode = modes(@mem[@ip])
+      a = read(@ip + 1, mode[0])
+      b = read(@ip + 2, mode[1])
+      r = @mem[@ip + 3]
+      raise StandardError, "unexpected mode: #{mode[2]}" if mode[2] != 0
+
+      @mem[r] = a + b
+      @ip += 4
+    end
+
+    def mul!
+      mode = modes(@mem[@ip])
+      a = read(@ip + 1, mode[0])
+      b = read(@ip + 2, mode[1])
+      r = @mem[@ip + 3]
+      raise StandardError, "unexpected mode: #{mode[2]}" if mode[2] != 0
+
+      @mem[r] = a * b
+      @ip += 4
+    end
+
+    def input!(&user_input)
+      mode = modes(@mem[@ip])
+      r = @mem[@ip + 1]
+      raise StandardError, "unexpected mode: #{mode[0]}" if mode[0] != 0
+
+      @mem[r] = input(&user_input)
+      @ip += 2
+    end
+
+    def output!(&user_output)
+      mode = modes(@mem[@ip])
+      output = read(@ip + 1, mode[0])
+      user_output.call output if block_given?
+      @ip += 2
+    end
+
+    def branch_if_not_zero!
+      mode = modes(@mem[@ip])
+      a = read(@ip + 1, mode[0])
+      b = read(@ip + 2, mode[1])
+      @ip = a.zero? ? @ip + 3 : b
+    end
+
+    def branch_if_zero!
+      mode = modes(@mem[@ip])
+      a = read(@ip + 1, mode[0])
+      b = read(@ip + 2, mode[1])
+      @ip = a.zero? ? b : @ip + 3
+    end
+
+    def less_than!
+      mode = modes(@mem[@ip])
+      a = read(@ip + 1, mode[0])
+      b = read(@ip + 2, mode[1])
+      r = @mem[@ip + 3]
+      raise StandardError, "unexpected mode: #{mode[2]}" if mode[2] != 0
+
+      @mem[r] = a < b ? 1 : 0
+      @ip += 4
+    end
+
+    def equal!
+      mode = modes(@mem[@ip])
+      a = read(@ip + 1, mode[0])
+      b = read(@ip + 2, mode[1])
+      r = @mem[@ip + 3]
+      raise StandardError, "unexpected mode: #{mode[2]}" if mode[2] != 0
+
+      @mem[r] = a == b ? 1 : 0
+      @ip += 4
+    end
+
+    def input
+      if block_given?
+        inp = yield
+        raise "Invalid input: #{inp}" unless inp.is_a?(Numeric)
+
+        return inp
+      end
+
+      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
+
+    def read(addr, mode)
+      param(@mem[addr], mode)
+    end
+  end
+end
diff --git a/2019/day7/part1.rb b/2019/day7/part1.rb
new file mode 100644
index 0000000..02cb85d
--- /dev/null
+++ b/2019/day7/part1.rb
@@ -0,0 +1,61 @@
+# frozen_string_literal: true
+
+require_relative 'intcode'
+
+def inputter(queue)
+  idx = 0
+  proc do
+    input = queue[idx]
+    idx += 1
+    input
+  end
+end
+
+class Amplifier
+  def initialize(memory, phase)
+    @memory = memory
+    @phase = phase
+  end
+
+  def amplify(input)
+    next_input = inputter([@phase, input])
+    computer = Intcode::Computer.new(@memory) do
+      inp = next_input.call
+      # print 'input> '
+      # puts inp
+      inp
+    end
+    output = nil
+    computer.on_output do |out|
+      output = out
+    end
+    computer.run
+    output
+  end
+end
+
+def thrust(program, phases)
+  a = Amplifier.new(program.as_memory, phases[0]).amplify(0)
+  b = Amplifier.new(program.as_memory, phases[1]).amplify(a)
+  c = Amplifier.new(program.as_memory, phases[2]).amplify(b)
+  d = Amplifier.new(program.as_memory, phases[3]).amplify(c)
+  e = Amplifier.new(program.as_memory, phases[4]).amplify(d)
+  e
+end
+
+program = Intcode.read(File.join(__dir__, 'input'))
+
+phase_space = [0, 1, 2, 3, 4].permutation(5)
+
+max_thrust = -Float::INFINITY
+max_phases = nil
+phase_space.each do |phases|
+  t = thrust(program, phases)
+  next unless t > max_thrust
+
+  max_thrust = t
+  max_phases = phases
+end
+
+pp max_phases
+puts max_thrust