merge sorted lists

merge.py

#merge sorted lists

def merge(l1, l2):
    i1, i2, i = 0, 0, 0
    N1, N2 = len(l1), len(l2)
    N = N1 + N2
    l = []
    for i in range(N):
        if i1 == N1:
            l.extend(l2[i2:])
            break
        if i2 == N2:
            l.extend(l1[i1:])
            break
        if l1[i1] < l2[i2]:
            l.append(l1[i1])
            i1 += 1
        else:
            l.append(l2[i2])
            i2 += 1
    return l

assert merge([1, 10, 100, 1000], [0, 2, 3, 200]) == [0, 1, 2, 3, 10, 100, 200, 1000]
assert merge([1, 10, 100, 1000], [0, 2, 200]) == [0, 1, 2, 10, 100, 200, 1000]
assert merge([1, 10, 100], [0, 2, 3, 200]) == [0, 1, 2, 3, 10, 100, 200]