python版归并排序

 1 def merge(ll, rr):
 2     i = 0
 3     j = 0
 4     num = []
 5     while i < len(ll) and j < len(rr):
 6         if ll[i] < rr[j]:
 7             num.append(ll[i])
 8             i += 1
 9         else:
10             num.append(rr[j])
11             j += 1
12     if i != len(ll):
13         num += ll[i:]
14     else:
15         num += rr[j:]
16     return num
17 def mergesort(num):
18     if len(num) == 1:
19         return num
20     ll = mergesort(num[len(num)>>1:])
21     rr = mergesort(num[:len(num)>>1])
22     num = merge(ll, rr)
23     return num
24 
25 print(mergesort([2,3,5,7,3,213,123,123,132,31,12,551,52,5,125,15,2]))