24 lines
576 B
Ruby
24 lines
576 B
Ruby
require 'prime'
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def four_digit_increasing_by(n)
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return [] if (9999 - (2*n)) < 0
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solutions = []
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(1..(9999 - (2*n))).each do |x|
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solutions << [x, x + n, x + (2 * n)]
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end
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solutions
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end
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def to_digit_list(num)
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num.to_s.split('').map(&:to_i)
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end
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def permutations?(number_list)
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comparison_digit_list = to_digit_list(number_list.first).sort
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number_list.all? { |x| to_digit_list(x).sort == comparison_digit_list }
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end
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def find_prime_permutations(n)
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four_digit_increasing_by(n).select { |x| permutations?(x) }.select { |x| x.all? { |y| Prime.prime?(y) } }
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end
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