python归并排序算法过程图示详解

def merge(a, b):

c = []

h = j = 0

while j < len(a) and h < len(b):

if a[j] < b[h]:

c.append(a[j])

j += 1

else:

c.append(b[h])

h += 1

if j == len(a):

for i in b[h:]:

c.append(i)

else:

for i in a[j:]:

c.append(i)

return c

def merge_sort(lists):

if len(lists) <= 1:

return lists

middle = len(lists)/2

left = merge_sort(lists[:middle])

right = merge_sort(lists[middle:])

return merge(left, right)

if __name__ == '__main__':

a = [4, 7, 8, 3, 5, 9]

print merge_sort(a)