leetcode 372. Super Pow

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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.

Example1:


a = 2
b = [3]

Result: 8

Example2:


a = 2
b = [1,0]

Result: 1024

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class Solution(object):
    def superPow(self, a, b):
        """
        :type a: int
        :type b: List[int]
        :rtype: int
        """
        #f(a,123456) = f(a,123450)*pow(a,6)=f(pow(a,10),12345)*pow(a,6)
        #n1*n2%k = (n1%k)(n2%k)%k
        if not b:return 1
        return pow(a, b.pop(), 1337)*self.superPow(pow(a, 10, 1337), b)%1337