'''
Given two numbers arr1 and arr2 in base -2, return the result of adding them together. 

Each number is given in array format:  as an array of 0s and 1s, from most significant bit to least significant bit.   For example, arr = [1,1,0,1] represents the number (-2)^3 + (-2)^2 + (-2)^0 = -3.   A number arr in array format is also guaranteed to have no leading zeros: either arr == [0] or arr[0] == 1. 

Return the result of adding arr1 and arr2 in the same format: as an array of 0s and 1s with no leading zeros. 

 

Example 1:

Input: arr1 = [1,1,1,1,1], arr2 = [1,0,1]
Output: [1,0,0,0,0]
Explanation: arr1 represents 11, arr2 represents 5, the output represents 16. 
 

Note:

1 <= arr1.length <= 1000
1 <= arr2.length <= 1000
arr1 and arr2 have no leading zeros
arr1[i] is 0 or 1
arr2[i] is 0 or 1
'''