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inopinatus/ackermann.rb

Created June 1, 2018 11:38
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Ackermann function in one line of Ruby as a hash default proc
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ackermann.rb
A = Hash.new { |a,(m,n)| a[[m,n]] = m==0 ? n+1 : n==0 ? a[[m-1,1]] : a[[m-1, a[[m, n-1]]]] } #=> {}
A[[3,4]] #=> 125
A.inspect #=> ... long
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