为什么归并排序如此有用？
1.
快捷和稳定
归并排序成为?一个非常棒的排序算法主要是因为它的快捷和稳
定。它的复杂度即使在最差情况下都是O(n log
n)。而快速排序
在最差情况下的复杂度是O(n^2)，当n=20的时候，它比归并要
慢4.6倍。
2.容易实现
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#coding:utf-8def merge_sort(array):
length =
len(array)
if
length <=
1: return
array
m =
length /
2
left =
array[:m]
right =
array[m:]
left =
merge_sort(left)
right =
merge_sort(right)
return
merge(left,right)
def
merge(left,right):
result =
[]
while
len(left)>0
and len(right)>0
:
if
left[0] <=
right[0]:
result.append(left.pop(0))
else:
result.append(right.pop(0))
result.extend(left)
result.extend(right)
return
result
if __name__ ==
‘__main__‘:
print
merge_sort([33,11,2,3,7,2234234234234234,4,23,2,3,4,7])
print
merge_sort([0,1,2,3,4,5,5,6,7,8,9])
print
merge_sort([9,8,7,6,5,5,4,3,2,1,0])
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