题目: Your task is to calculate a^b mod 1337 where a is a positive integer and b is an extremely large positive integer given in the form of an array. 求a的b次方mod 1337,其中b是一个extremely large的数,以至于需要用整数数组来存储. 引理:(a × b)mod M = ((a mod M) * (b mod M)) mod M