1 files changed, 116 insertions, 0 deletions
diff --git a/2022/day2.rb b/2022/day2.rb
new file mode 100644
index 0000000..bc4ade5
--- /dev/null
+++ b/2022/day2.rb
@@ -0,0 +1,116 @@
+TEST_S = <<-EOF
+A Y
+B X
+C Z
+EOF
+
+def score(picked_item, outcome)
+  fail "Wrong picked item '#{picked_item}'" unless picked_item
+  outcome_score = case outcome
+                  when :win
+                    6
+                  when :draw
+                    3
+                  when :lose
+                    0
+                  end
+  picked_score = case picked_item
+                 when /A|X/
+                   1
+                 when /B|Y/
+                   2
+                 when /C|Z/
+                   3
+                 end
+  #puts "#{outcome_score} + #{picked_score}"
+  return outcome_score + picked_score
+end
+
+def guessed_strategy(line)
+  outcome_map = {
+    'A X' => :draw,
+    'A Y' => :win,
+    'A Z' => :lose,
+    'B X' => :lose,
+    'B Y' => :draw,
+    'B Z' => :win,
+    'C X' => :win,
+    'C Y' => :lose,
+    'C Z' => :draw
+  }
+  return outcome_map[line]
+end
+
+def correct_strategy(item1, item2)
+  return :win if item2 == 'Z'
+  return :draw if item2 == 'Y'
+  return :lose if item2 == 'X'
+end
+
+def what_to_choose(oponent_shape, outcome)
+  case outcome
+  when :draw
+    return oponent_shape
+  when :win
+    case oponent_shape
+    when 'A'
+      return 'B'
+    when 'B'
+      return 'C'
+    when 'C'
+      return 'A'
+    else
+      fail "Don't know this shape '#{oponent_shape}'"
+    end
+  when :lose
+    case oponent_shape
+    when 'A'
+      return 'C'
+    when 'B'
+      return 'A'
+    when 'C'
+      return 'B'
+    else
+      fail "Don't know this shape '#{oponent_shape}'"
+    end
+  else
+    fail "Don't know this outcome '#{outcome}'"
+  end
+end
+
+def part1(filename)
+  score = 0
+  File.open(filename) do |f|
+    scores = f.readlines.map do |line|
+      item1, item2 = line.chomp.split()
+      outcome = guessed_strategy(line.chomp)
+      score(item2, outcome)
+    end
+
+    score = scores.sum
+  end
+  score
+end
+
+def part2(filename)
+  score = 0
+  File.open(filename) do |f|
+    scores = f.readlines.map do |line|
+      item1, item2 = line.chomp.split()
+      outcome = correct_strategy(item1, item2)
+      shape = what_to_choose(item1, outcome)
+      score(shape, outcome)
+    end
+
+    score = scores.sum
+  end
+  score
+end
+
+#puts part1('./day2-test.txt')
+#puts part1('./day2.txt')
+
+
+puts 'Part2'
+puts part2('./day2-test.txt')
+puts part2('./day2.txt')