372. Super Pow

Your task is to calculate ab mod 1337 where a is a positive integer and b is an extremely large positive integer given in the form of an array.

Example 1:

Input: a = 2, b = [3]
Output: 8

Example 2:

Input: a = 2, b = [1,0]
Output: 1024

Example 3:

Input: a = 1, b = [4,3,3,8,5,2]
Output: 1

Example 4:

Input: a = 2147483647, b = [2,0,0]
Output: 1198

Constraints:

• 1 <= a <= 231 - 1
• 1 <= b.length <= 2000
• 0 <= b[i] <= 9
• b doesn't contain leading zeros.

# @lc code=start
using LeetCode

function super_pow(a::Int, b::Vector{Int})
    md, ϕ = 1337, 1140
    n = length(b)
    n == 0 && return 1
    e = 0
    a %= md
    for digit in b
        e = (10 * e + digit) % ϕ
    end
    powermod(a, e, md)
end
# @lc code=end

super_pow (generic function with 1 method)

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