LeetCode (Python): Merge Sorted Array

Given two sorted integer arrays A and B, merge B into A as one sorted array.

Note:
You may assume that A has enough space (size that is greater or equal to m + n) to hold additional elements from B. The number of elements initialized in A and B are mand n respectively.

Solution:

If we start adding the elements from the end to the beginning, once an element is inserted it does not have to be moved

class Solution:
    # @param A  a list of integers
    # @param m  an integer, length of A
    # @param B  a list of integers
    # @param n  an integer, length of B
    # @return nothing
    def merge(self, A, m, B, n):
        indexA = m-1;
        indexB = n-1;
        while indexA >=0 and indexB>=0:
            if A[indexA] > B[indexB]:
                A[indexA+indexB+1] = A[indexA]
                indexA -= 1
            else:
                A[indexA+indexB+1] = B[indexB]
                indexB -= 1
        while indexB >= 0:
             A[indexB] = B[indexB]
             indexB -= 1