Merge two sorted arrays. (using constant space)

sorted_arrays_merge.py

a = [2]
b = [-10,3]

a_pointer = len(a)-1
b_pointer = len(b)-1

for _ in range(len(b)): a.append(0)

l_pointer = len(a)-1

while(a_pointer >= 0 and b_pointer >= 0):
  if(a[a_pointer] > b[b_pointer]):
    a[l_pointer] = a[a_pointer]
    a_pointer -= 1
    l_pointer -=1
  else:
    a[l_pointer] = b[b_pointer]  
    l_pointer -= 1
    b_pointer -= 1

if(a_pointer < 0 and b_pointer>=0):
  while(l_pointer>=0):
    a[l_pointer] = b[b_pointer]
    l_pointer -=1
    b_pointer-=1

print(a)

# time complexity = O(m+n)
# Space complexity = O(n)