989 Add to Array-Form of Integer.py

#!/usr/bin/python3
"""
For a non-negative integer X, the array-form of X is an array of its digits in
left to right order.  For example, if X = 1231, then the array form is [1,2,3,1].

Given the array-form A of a non-negative integer X, return the array-form of the integer X+K.



Example 1:

Input: A = [1,2,0,0], K = 34
Output: [1,2,3,4]
Explanation: 1200 + 34 = 1234
Example 2:

Input: A = [2,7,4], K = 181
Output: [4,5,5]
Explanation: 274 + 181 = 455
Example 3:

Input: A = [2,1,5], K = 806
Output: [1,0,2,1]
Explanation: 215 + 806 = 1021
Example 4:

Input: A = [9,9,9,9,9,9,9,9,9,9], K = 1
Output: [1,0,0,0,0,0,0,0,0,0,0]
Explanation: 9999999999 + 1 = 10000000000
"""
from typing import List
from collections import deque


class Solution:
    def addToArrayForm(self, A: List[int], K: int) -> List[int]:
        """
        carry
        """
        carry = K
        for i in range(len(A)-1, -1, -1):
            A[i] += carry
            carry = A[i] // 10
            A[i] %= 10
            
        head = deque()
        while carry:
            head.appendleft(carry % 10)
            carry //= 10

        return list(head) + A