My implementation of merging two sorted lists in linear time - what could be improved?

Question

Fromg Google\'s Python Class:

E. Given two lists sorted in increasing order, create and return a merged
list of all the elements in sorted order. You may mod         


        

Answer 1

I agree with other answers that extending and sorting is the most straightforward way, but if you must merge, this will be a little faster because it does not make two calls to len every iteration nor does it do a bounds check. The Python pattern, if you could call it that, is to avoid testing for a rare case and catch the exception instead.

def linear_merge(list1, list2):
    merged_list = []
    i = 0
    j = 0

    try:
        while True:
            if list1[i] <= list2[j]:
                merged_list.append(list1[i])
                i += 1
            else:
                merged_list.append(list2[j])
                j += 1
    except IndexError:
        if i == len(list1):
            merged_list.extend(list2[j:])
        if j == len(list2):
            merged_list.extend(list1[i:])
    return merged_list

edit Optimized per John Machin's comment. Moved try outside of while True and extended merged_list upon exception.