sidef/scripts/RosettaCode/ramsey_s_theorem.sf

#!/usr/bin/ruby

#
## https://rosettacode.org/wiki/Ramsey%27s_theorem
#

var a = 17.of { 17.of(0) }

17.times{|i| a[i][i] = '-' }
4.times { |k|
  17.times { |i|
    var j = ((i + 1<<k) % 17)
    a[i][j] = (a[j][i] = 1)
  }
}

a.each {|row| say row.join(' ') }

combinations(17, 4, { |*quartet|
  var links = quartet.combinations(2).map{|p| a.dig(p...) }.sum
  ((0 < links) && (links < 6)) || die "Bogus!"
})
say "Ok"