mirror of
https://github.com/TheAlgorithms/Python.git
synced 2024-11-24 13:31:07 +00:00
7592cba417
* added sol3.py for problem_20 * added sol4.py for problem_06 * ran `black .` on `\Python`
49 lines
937 B
Python
49 lines
937 B
Python
def merge(a, b, m, e):
|
|
l = a[b : m + 1]
|
|
r = a[m + 1 : e + 1]
|
|
k = b
|
|
i = 0
|
|
j = 0
|
|
while i < len(l) and j < len(r):
|
|
# change sign for Descending order
|
|
if l[i] < r[j]:
|
|
a[k] = l[i]
|
|
i += 1
|
|
else:
|
|
a[k] = r[j]
|
|
j += 1
|
|
k += 1
|
|
while i < len(l):
|
|
a[k] = l[i]
|
|
i += 1
|
|
k += 1
|
|
while j < len(r):
|
|
a[k] = r[j]
|
|
j += 1
|
|
k += 1
|
|
return a
|
|
|
|
|
|
def mergesort(a, b, e):
|
|
"""
|
|
>>> mergesort([3,2,1],0,2)
|
|
[1, 2, 3]
|
|
>>> mergesort([3,2,1,0,1,2,3,5,4],0,8)
|
|
[0, 1, 1, 2, 2, 3, 3, 4, 5]
|
|
"""
|
|
if b < e:
|
|
m = (b + e) // 2
|
|
# print("ms1",a,b,m)
|
|
mergesort(a, b, m)
|
|
# print("ms2",a,m+1,e)
|
|
mergesort(a, m + 1, e)
|
|
# print("m",a,b,m,e)
|
|
merge(a, b, m, e)
|
|
return a
|
|
|
|
|
|
if __name__ == "__main__":
|
|
import doctest
|
|
|
|
doctest.testmod()
|