problem26-solved.rb

# A unit fraction contains 1 in the numerator. The decimal representation of the unit fractions with denominators 2 to 10 are given:
# 1/2	= 	0.5
# 1/3	= 	0.(3)
# 1/4	= 	0.25
# 1/5	= 	0.2
# 1/6	= 	0.1(6)
# 1/7	= 	0.(142857)
# 1/8	= 	0.125
# 1/9	= 	0.(1)
# 1/10	= 	0.1
# Where 0.1(6) means 0.166666..., and has a 1-digit recurring cycle. It can be seen that 1/7 has a 6-digit recurring cycle.
# Find the value of d < 1000 for which 1/d contains the longest recurring cycle in its decimal fraction part.
require 'flt'
include Flt
DecNum.context.precision = 2000
pre = ""
results = []
highest_str = ""

for i in (1..1000)
	max_seq = ""

	dec = DecNum(1)/DecNum(i)
	pre = dec.to_s.split('.').last

	for x in (1..pre.length)
		if pre[0..x] == pre[x+1..2*x+1]
			max_seq = pre[0..x]
			results << [i, max_seq.to_s, max_seq.to_s.length]

			if highest_str.length < x
				highest_str = pre[0..x]
				puts ("Longest decimal repeating sequence of  " + i.to_s + "  is " + x.to_s)
			end
			break
		end
	end
end