交換兩項位置方法：
# -*- coding: utf-8 -*-
defswap
(lyst, i, j)
: temp = lyst[i]
lyst[i]
= lyst[j]
lyst[j]
= temp
選擇排序
defselectionsort
(lyst)
: i =
0while i <
len(lyst)-1
: minindex = i
j = i +
1while j <
len(lyst)
:if lyst[j]
< lyst[minindex]
: minindex = j
j +=
1if minindex != i:
swap(lyst, minindex, i)
i +=
1排序前:[9
,6,7
,11,3
,1,0
,-78,
2,-5
,10,1
]排序後：[-
78,-5
,0,1
,1,2
,3,6
,7,9
,10,11
]氣泡排序
defbubblesort
(lyst)
: n =
len(lyst)
while n >1:
i =1while i < n:
if lyst[i]
< lyst[i -1]
: swap(lyst, i, i -1)
i +=
1 n -=
1排序前:[7
,1,2
,5,0
,-1,
-56,2
,2,2
,1,0
]排序後：[-
56,-1
,0,0
,1,1
,2,2
,2,2
,5,7
]插入排序
definsertionsort
(lyst)
: i =
1while i <
len(lyst)
: itemtoinsert = lyst[i]
j = i -
1while j >=0:
if itemtoinsert < lyst[j]
: lyst[j +1]
= lyst[j]
j -=
1else
:break
lyst[j +1]
= itemtoinsert
i +=
1排序前:[9
,1,5
,10,-
1,13,
5,8,
2,1,
17,4]
排序後：[-
1,1,
1,2,
4,5,
5,8,
9,10,
13,17]
快速排序
defquicksort
(lyst)
: quicksorthelper(lyst,0,
len(lyst -1)
)def
quicksorthelper
(lyst, left, right)
:if left < right:
pivotlocation = partition(lyst, left, right)
quicksorthelper(lyst, left, pivotlocation -1)
quicksorthelper(lyst, pivotlocation +
1, right)
defpartition
(lyst, left, right)
: middle =
(left + right)//2
pivot = lyst[middle]
lyst[middle]
= lyst[right]
lyst[right]
= pivot
boundary = left
for index in
range
(left, right)
:if lyst[index]
< pivot:
swap(lyst, index, boundary)
boundary +=
1 swap(lyst, right, boundary)
return boundary
排序前:[9
,11,5
,1,-
1,113,5,
-8,20
,1,17
,4]排序後：[-
8,-1
,1,1
,4,5
,5,9
,11,17
,20,113
]合併排序
defmergesort
(lyst)
: copybuffer =
for i in
range
(len
(lyst)):
none
) mergesorthelper(lyst, copybuffer,0,
len(lyst)-1
)def
mergesorthelper
(lyst, copybuffer, low, high)
:if low < high:
middle =
(low + high)//2
mergesorthelper(lyst, copybuffer, low, middle)
mergesorthelper(lyst, copybuffer, middle +
1, high)
merge(lyst, low, middle, high)
defmerge
(lyst, low, middle, high)
: i1 = low
i2 = middle +
1for i in
range
(low, high +1)
:if i1 > middle:
copybuffer[i]
= lyst[i2]
i2 +=
1elif i2 > high:
copybuffer[i]
= lyst[i1]
i1 +=
1elif lyst[i1]
< lyst[i2]
: copybuffer[i]
= lyst[i1]
i1 +=
1else
: copybuffer[i]
= lyst[i2]
i2 +=
1for i in
range
(low, high +1)
: lyst[i]
= copybuffer[i]
排序前:[19
,4,51
,10,-
41,113,15,
-84,210,11
,177,4
]排序後：[-
84,-41
,4,4
,10,11
,15,19
,51,113
,177
,210
]
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