How to define a recursive function to merge two sorted lists and return a new list with a increasing order in Python?

Question

I want to define a recursive function to merge two sorted lists (these two lists are sorted) and return a new list containing all the values in both argument lists with a incre

Answer 1

Instead of return, you should add it to the alist as like below.

def combine(a, b):
    alist = []
    if a == [] and b == []:
       return alist
    if a != [] and b == []:
       return alist + a
    if a == [] and b != []:
       return alist + b
    if a != [] and b != []:
       if a[0] <= b[0]:
          alist.append(a[0])
          alist = alist +  combine(a[1:], b)
       if a[0] > b[0]:
          alist.append(b[0])
          alist = alist +  combine(a, b[1:])
    return alist