python版归并排序

def merge(ll, rr):
    i = 0
    j = 0
    num = []
    while i < len(ll) and j < len(rr):
        if ll[i] < rr[j]:
            num.append(ll[i])
            i += 1
        else:
            num.append(rr[j])
            j += 1
    if i != len(ll):
        num += ll[i:]
    else:
        num += rr[j:]
    return num
def mergesort(num):
    if len(num) == 1:
        return num
    ll = mergesort(num[len(num)>>1:])
    rr = mergesort(num[:len(num)>>1])
    num = merge(ll, rr)
    return num

print(mergesort([2,3,5,7,3,213,123,123,132,31,12,551,52,5,125,15,2]))

python的语法就是如此简洁