Year 2016: Day 02

README.md

@@ -8,7 +8,7 @@ I'm also adding notes that may be useful if you're learning Ruby.
 
 Notes for solving:
 * [2015, complete](year_2015.md)
-* [2016, up to day 01](year_2016.md)
+* [2016, up to day 02](year_2016.md)
 * [2023, up to day 03](year_2023.md)
 
 # How to use

spec/year_2016/day_02_input

@@ -0,0 +1,5 @@
+UULLULLUULLLURDLDUURRDRRLDURDULLRURDUDULLLUULURURLRDRRRRULDRUULLLLUUDURDULDRRDRUDLRRLDLUDLDDRURURUURRRDDDLLRUDURDULUULLRRULLRULDUDRDRLDLURURUDDUDLURUDUDURLURURRURLUDDRURRDLUURLLRURRDUDLULULUDULDLLRRRDLRDLDUDRDDDRRUURRRRRUURRDRRDLURDRRURDLLUULULLRURDLDDDRRLLRRUURULURUUDDLRRUDDRURUUDLRLRDLRURRRDULLDLRUDDUULRDULURUURDULUDLLRRLDDLRDLRUDRLDDRLRRRDURDULLRRRDRRLUURURDRRDRRLDLUDURURLDUURDRUDRDDRLDRRLDLURURULLUURUDUUDLRLL
+LLLULLULDDULRLLURLLLRUUDDLRUULRLULLDLLRRDRLRLRLLDRUUURULDRDDLUDLLDUDULLLRLULLLRULDRDRUDLLRLRLLUDULRRRLDRUULDDULLDULULLUDUDLDRDURDLDLLDUDRRRDLUURRUURULLURLDURLRRLLDDUUULDRLUUDUDLURLULUDURRDRLLDDDDDRRULLRLDULULDDRUURRDLUDDDUDURDDRDRULULLLLUURDURUUUULUDLRURRULRDDRURURLLRLUUDUUURDLLDDLUDRLLLUDLLLLULRLURDRRRDUUDLLDLDDDURRDDRURUURDDRURRLDDDURDLLUURUUULRLUURRUDRLLDLURDUDRLULDLRLULULUDDLRDUDRUDLUULUULDURDRRRRLRULLUDRDDRDLDUDRDRRLDLLLLUDDLRULDLLDDUULDDRRULRRUURUDRDURLLLDDUUDRUUDLULLDR
+UDUUULLDDDDLUDLDULRLRDLULLDDRULDURRLURRUDLRRUDURRDUDRRRUULRLLRLUDLDRRDUURDDRDRDUUUDUDLDLLRRLUURLUUUDDDUURLULURRLURRRDRDURURUDRLRUURUDRUDDDRDRDLDRDURDLDRRDUUDLLURLDDURRRLULDRDRLLRLLLRURLDURDRLDRUURRLDLDRLDDDRLDLRLDURURLLLLDDRDUDLRULULLRDDLLUDRDRRLUUULDRLDURURDUDURLLDRRDUULDUUDLLDDRUUULRRULDDUDRDRLRULUUDUURULLDLLURLRRLDDDLLDRRDDRLDDLURRUDURULUDLLLDUDDLDLDLRUDUDRDUDDLDDLDULURDDUDRRUUURLDUURULLRLULUURLLLLDUUDURUUDUULULDRULRLRDULDLLURDLRUUUDDURLLLLDUDRLUUDUDRRURURRDRDDRULDLRLURDLLRRDRUUUURLDRURDUUDLDURUDDLRDDDDURRLRLUDRRDDURDDRLDDLLRR
+ULDRUDURUDULLUDUDURLDLLRRULRRULRUDLULLLDRULLDURUULDDURDUUDLRDRUDUDDLDRDLUULRRDLRUULULUUUDUUDDRDRLLULLRRDLRRLUDRLULLUUUUURRDURLLRURRULLLRLURRULRDUURRLDDRRDRLULDDRRDRLULLRDLRRURUDURULRLUDRUDLUDDDUDUDDUDLLRDLLDRURULUDRLRRULRDDDDDRLDLRRLUUDLUURRDURRDLDLDUDRLULLULRLDRDUDLRULLULLRLDDRURLLLRLDDDLLLRURDDDLLUDLDLRLUULLLRULDRRDUDLRRDDULRLLDUURLLLLLDRULDRLLLUURDURRULURLDDLRRUDULUURRLULRDRDDLULULRRURLDLRRRUDURURDURDULURULLRLDD
+DURLRRRDRULDLULUDULUURURRLULUDLURURDDURULLRRUUDLRURLDLRUDULDLLRRULLLLRRLRUULDLDLLRDUDLLRLULRLLUUULULRDLDLRRURLUDDRRLUUDDRRUDDRRURLRRULLDDULLLURRULUDLRRRURRULRLLLRULLRRURDRLURULLDULRLLLULLRLRLLLDRRRRDDDDDDULUUDUDULRURDRUDRLUULURDURLURRDRRRRDRRLLLLUDLRRDURURLLULUDDLRLRLRRUURLLURLDUULLRRDURRULRULURLLLRLUURRULLLURDDDRURDUDDULLRULUUUDDRURUUDUURURRDRURDUDRLLRRULURUDLDURLDLRRRRLLUURRLULDDDUUUURUULDLDRLDUDULDRRULDRDULURRUURDU

spec/year_2016/day_02_spec.rb

@@ -0,0 +1,38 @@
+require 'year_2016/day_02'
+
+describe Year2016::Day02 do
+  subject(:sample) do
+    <<~HEREDOC
+      ULL
+      RRDDD
+      LURDL
+      UUUUD
+    HEREDOC
+  end
+
+  context 'when Part 1' do
+    it 'gives a final result' do
+      expect(described_class.new(sample, true).code).to eq('1985')
+    end
+  end
+
+  context 'when Part 2' do
+    it 'gives a final result' do
+      expect(described_class.new(sample).code).to eq('5DB3')
+    end
+  end
+
+  context 'when Results' do
+    subject(:input_data) do
+      File.read('spec/year_2016/day_02_input')
+    end
+
+    it 'correctly answers part 1' do
+      expect(described_class.new(input_data, true).code).to eq('45973')
+    end
+
+    it 'correctly answers part 2' do
+      expect(described_class.new(input_data).code).to eq('27CA4')
+    end
+  end
+end

year_2016.md

@@ -13,3 +13,18 @@ Year2015::Day01
 ```
 
 There really is nothing specifically hard here, it's all about knowing when to properly break out of a loop.
+
+## Day 02: Bathroom Security
+
+```
+Year2016::Day02
+  when Part 1
+    gives a final result
+  when Part 2
+    gives a final result
+  when Results
+    correctly answers part 1
+    correctly answers part 2
+```
+
+While reviewing [another code solution for the previous day's exercise](https://github.com/rHermes/adventofcode/blob/master/2016/01/y2016_d01_p02.py), I was intrigued by a very interesting piece of code: the author had treated the turning of left and right into transition paths from one state to another. While the situation felt like overkill to me in that case, it proved to work perfectly for today's exercise.

year_2016/day_02.rb

@@ -0,0 +1,69 @@
+class Year2016
+  class Day02
+    # Reminder:
+    # 1 2 3
+    # 4 5 6
+    # 7 8 9
+    BUTTONS_V1 = {
+      '1' => { 'R' => '2', 'D' => '4' },
+      '2' => { 'L' => '1', 'R' => '3', 'D' => '5' },
+      '3' => { 'L' => '2', 'D' => '6' },
+      '4' => { 'U' => '1', 'R' => '5', 'D' => '7' },
+      '5' => { 'U' => '2', 'L' => '4', 'R' => '6', 'D' => '8' },
+      '6' => { 'L' => '5', 'U' => '3', 'D' => '9' },
+      '7' => { 'R' => '8', 'U' => '4' },
+      '8' => { 'L' => '7', 'R' => '9', 'U' => '5' },
+      '9' => { 'L' => '8', 'U' => '6' }
+    }.freeze
+
+    # Reminder:
+    #     1
+    #   2 3 4
+    # 5 6 7 8 9
+    #   A B C
+    #     D
+    BUTTONS_V2 = {
+      '1' => { 'D' => '3' },
+
+      '2' => { 'R' => '3', 'D' => '6' },
+      '3' => { 'L' => '2', 'U' => '1', 'D' => '7', 'R' => '4' },
+      '4' => { 'L' => '3', 'D' => '8' },
+
+      '5' => { 'R' => '6' },
+      '6' => { 'U' => '2', 'L' => '5', 'R' => '7', 'D' => 'A' },
+      '7' => { 'U' => '3', 'L' => '6', 'R' => '8', 'D' => 'B' },
+      '8' => { 'U' => '4', 'L' => '7', 'R' => '9', 'D' => 'C' },
+      '9' => { 'L' => '8' },
+
+      'A' => { 'R' => 'B', 'U' => '6' },
+      'B' => { 'L' => 'A', 'U' => '7', 'D' => 'D', 'R' => 'C' },
+      'C' => { 'L' => 'B', 'U' => '8' },
+
+      'D' => { 'U' => 'B' }
+    }.freeze
+
+    def initialize(input_data, input_part_one = false)
+      @input = input_data
+      @version = input_part_one ? 1 : 2
+    end
+
+    def do_moves(starter, line)
+      curpos = starter
+      line.each_char do |direction|
+        nextpos = (@version == 1 ? BUTTONS_V1 : BUTTONS_V2)[curpos][direction]
+
+        curpos = nextpos if nextpos
+      end
+      curpos
+    end
+
+    def code
+      @code ||= @input.split("\n").each_with_object([]) do |line, code|
+        # puts "=> #{code[-1] || '?'} => #{line}"
+        result = do_moves(code[-1] || '5', line)
+
+        code << result
+      end.join
+    end
+  end
+end