# Python排序算法

• 冒泡排序
• 合併排序
• 插入排序
• 希爾排序
• 選擇排序

## 冒泡排序

``````def bubblesort(list):

# Swap the elements to arrange in order
for iter_num in range(len(list)-1,0,-1):
for idx in range(iter_num):
if list[idx]>list[idx+1]:
temp = list[idx]
list[idx] = list[idx+1]
list[idx+1] = temp

list = [19,2,31,45,6,11,121,27]
bubblesort(list)
print(list)``````

``[2, 6, 11, 19, 27, 31, 45, 121]``

## 合併排序

``````def merge_sort(unsorted_list):
if len(unsorted_list) <= 1:
return unsorted_list
# Find the middle point and devide it
middle = len(unsorted_list) // 2
left_list = unsorted_list[:middle]
right_list = unsorted_list[middle:]

left_list = merge_sort(left_list)
right_list = merge_sort(right_list)
return list(merge(left_list, right_list))

# Merge the sorted halves

def merge(left_half,right_half):

res = []
while len(left_half) != 0 and len(right_half) != 0:
if left_half[0] < right_half[0]:
res.append(left_half[0])
left_half.remove(left_half[0])
else:
res.append(right_half[0])
right_half.remove(right_half[0])
if len(left_half) == 0:
res = res + right_half
else:
res = res + left_half
return res

unsorted_list = [64, 34, 25, 12, 22, 11, 90]

print(merge_sort(unsorted_list))``````

``[11, 12, 22, 25, 34, 64, 90]``

## 插入排序

``````def insertion_sort(InputList):
for i in range(1, len(InputList)):
j = i-1
nxt_element = InputList[i]
# Compare the current element with next one
while (InputList[j] > nxt_element) and (j >= 0):
InputList[j+1] = InputList[j]
j=j-1
InputList[j+1] = nxt_element

list = [19,2,31,45,30,11,121,27]
insertion_sort(list)
print(list)``````

``[2, 11, 19, 27, 30, 31, 45, 121]``

## 希爾排序

``````def shellSort(input_list):

gap = len(input_list) / 2
while gap > 0:

for i in range(gap, len(input_list)):
temp = input_list[i]
j = i
# Sort the sub list for this gap

while j >= gap and input_list[j - gap] > temp:
input_list[j] = input_list[j - gap]
j = j-gap
input_list[j] = temp

# Reduce the gap for the next element

gap = gap/2

list = [19,2,31,45,30,11,121,27]

shellSort(list)
print(list)``````

``[2, 11, 19, 27, 30, 31, 45, 121]``

## 選擇排序

``````def selection_sort(input_list):

for idx in range(len(input_list)):

min_idx = idx
for j in range( idx +1, len(input_list)):
if input_list[min_idx] > input_list[j]:
min_idx = j
# Swap the minimum value with the compared value

input_list[idx], input_list[min_idx] = input_list[min_idx], input_list[idx]

l = [19,2,31,45,30,11,121,27]
selection_sort(l)
print(l)``````

``[2, 11, 19, 27, 30, 31, 45, 121]``