32 lines
783 B
Ruby
32 lines
783 B
Ruby
descr=%{
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Let d(n) be defined as the sum of proper divisors of n (numbers less than n which divide evenly into n).
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If d(a) = b and d(b) = a, where a ≠ b, then a and b are an amicable pair and each of a and b are called amicable numbers.
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For example, the proper divisors of 220 are 1, 2, 4, 5, 10, 11, 20, 22, 44, 55 and 110; therefore d(220) = 284. The proper divisors of 284 are 1, 2, 4, 71 and 142; so d(284) = 220.
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Evaluate the sum of all the amicable numbers under 10000.
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}
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def d(n)
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sum=0
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(1..n/2).each do |i|
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if n % i == 0
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sum += i
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end
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end
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return sum
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end
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h={}
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(1..10000).each do |n|
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h[n]=d(n)
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end
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sum=0
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h.each do |n,m|
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if h[m] == n && n != m
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puts "#{m}\t#{n}"
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sum+=n
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end
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end
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puts sum
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