52 lines
963 B
Ruby
52 lines
963 B
Ruby
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#!/usr/bin/env ruby
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class Integer
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define_method(:"||") do |v|
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to_s.concat(v.to_s).to_i
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end
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end
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problem = 7
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input = File.readlines("#{problem}.input").map(&:strip)
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#input = DATA.read.split("\n")
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.map do |line|
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solution, expression = line.split(": ")
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[
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solution.to_i,
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expression.split(" ").map { _1.strip.to_i }
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]
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end
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OPERATIONS = [:+, :*, :"||"]
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def solve(equation)
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equation[1..].each_slice(2).to_a
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.reduce(equation[0]) do |acc, (operation, number)|
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acc = acc.public_send(operation, number); acc
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end
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end
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def possibilities(solution, numbers)
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OPERATIONS.repeated_permutation(numbers.size - 1)
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.map { numbers.zip(_1).flatten.compact }
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.any? { solve(_1) == solution }
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end
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result = input
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.select { possibilities(_1.first, _1.last) }
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.map { _1.first }
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.sum
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p result
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__END__
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