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twentyone.rb
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twentyone.rb
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# frozen_string_literal: true
# Day 21
class TwentyOne < Day
# Equation
class Equation
attr_reader :left, :right, :operation
def initialize(left:, right:, operation:)
@left = left
@right = right
@operation = operation
end
end
# Value
class Value
attr_reader :value
def initialize(value)
@value = value
end
end
# Tree of expression
class ExpressionTree
attr_reader :operation, :left, :right
def initialize(expression, values)
@operation = expression.operation
@left = if values[expression.left].is_a? Equation
ExpressionTree.new(values[expression.left], values)
else
values[expression.left].value
end
@right = if values[expression.right].is_a? Equation
ExpressionTree.new(values[expression.right], values)
else
values[expression.right].value
end
end
end
def initialize
super
@tree = ExpressionTree.new(values['root'], values)
end
def values
@values ||= File.readlines('twentyone.txt', chomp: true).map do |line|
name, part = line.split(':')
parts = part.split(%r{\+|-|\*|/})
[
name,
if parts.size == 1
Value.new(parts.first.to_i)
else
Equation.new(left: parts.first.strip, right: parts.second.strip, operation: part[6])
end
]
end.to_h
end
def part_a
solve(@tree)
end
def solve(node)
return node if node.is_a? Numeric
operation = node.operation.to_sym.to_proc
operation.call(solve(node.left), solve(node.right))
end
def part_b; end
end