Project Euler 26 计算小数位循环的位数

A unit fraction contains 1 in the numerator. The decimal representation of the unit fractions with denominators 2 to 10 are given:

¹/₂= 0.5¹/₃= 0.(3)¹/₄= 0.25¹/₅= 0.2¹/₆= 0.1(6)¹/₇= 0.(142857)¹/₈= 0.125¹/₉= 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.

解析：费马小定理的应用

def recu_cycle(d):for t in range(1,d):if 1 == 10**t % d:return t;return 0longest = max(recu_cycle(i) for i in range(2,1001))print [i for i in range(2,1001) if recu_cycle(i) == longest][0]