problem 51 solution
parent
38412d7d78
commit
84b7ee2f31
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@ -64,5 +64,13 @@ module Euler
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true
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end
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def non_empty_subsets(list)
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(1..list.count).map { |x| list.combination(x).to_a }.flatten(1)
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end
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def powerset(list)
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(0..list.count).map { |x| list.combination(x).to_a }.flatten(1)
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end
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end
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end
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@ -1,28 +1,61 @@
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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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require_relative 'euler'
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# i = 0
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# Prime.take_while do |p|
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# i += 1
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# result = false
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# digits = p.to_digit_list
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# Euler.non_empty_subsets(digits).each do |index_list|
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# related_primes = []
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# ('1'..'9').each do |j|
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# copied_digit_list = Array.new(digits)
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# index_list.each do |index|
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# copied_digit_list[index] = j
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# end
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# new_num = Euler.from_digit_list(copied_digit_list)
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# related_primes.push(new_num) if new_num.prime? and !related_primes.include?(new_num)
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# end
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# if related_primes.count == 7
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# puts p
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# puts '---'
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# puts related_primes.inspect
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# result = related_primes
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# end
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# end
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# puts result if i % 1000
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# result == false
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# end
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def bitmasks(length)
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(1..2**length-1).map { |n| n.to_s(2) }.map { |s| s.rjust(4, '0')}.map { |s| s.split('').map(&:to_i)}
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end
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def six_multiples(x)
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[x, 2 * x, 3 * x, 4 * x, 5 * x, 6 * x]
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end
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def infinite_series
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Enumerator.new do |y|
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n = 1
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loop do
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y << n
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n += 1
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def prime_digit_replacement(number, mask)
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digits = number.to_digit_list
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related_primes = []
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('0'..'9').each do |j|
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copied_digit_list = Array.new(digits)
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mask.each_with_index do |bit, index|
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copied_digit_list[index] = j if bit == 1
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end
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new_num = Euler.from_digit_list(copied_digit_list)
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related_primes.push(new_num) if new_num.prime? and !related_primes.include?(new_num) and new_num.to_digit_list.count == digits.count
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end
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related_primes
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end
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def same_digit_six_multiples
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series = infinite_series
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n = series.next
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loop do
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result = permutations?(six_multiples(n))
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return six_multiples(n) if result
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n = series.next
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def solution(family_count)
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result = false
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Prime.take_while do |p|
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digits = p.to_digit_list
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bitmasks(digits.count).each do |mask|
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related_primes = prime_digit_replacement(p, mask)
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if related_primes.count == family_count and related_primes.include?(p)
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result = p
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break
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end
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end
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result == false
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end
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result
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end
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@ -0,0 +1,28 @@
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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 six_multiples(x)
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[x, 2 * x, 3 * x, 4 * x, 5 * x, 6 * x]
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end
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def infinite_series
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Enumerator.new do |y|
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n = 1
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loop do
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y << n
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n += 1
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end
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end
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end
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def same_digit_six_multiples
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series = infinite_series
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n = series.next
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loop do
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result = permutations?(six_multiples(n))
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return six_multiples(n) if result
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n = series.next
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end
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end
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