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8 years ago
# 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
#
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# 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.
def longest_permutation(denominator):
mod_list = []
modulo = 1.0
while True:
modulo *= 10
if modulo in mod_list:
break
mod_list.append(modulo)
modulo %= denominator
return len(mod_list)
longest_perm = 0
longest_perm_denominator = 0
for i in range(1, 1000):
perm_num = longest_permutation(i)
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if longest_perm < perm_num:
longest_perm = perm_num
longest_perm_denominator = i
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print(longest_perm_denominator)
print(longest_perm)