排序方法总体分为三类：
| 方法类别 | 低阶 | 高阶 |
| 插入排序 | 直接插入排序 | 希尔排序 |
| 选择排序 | 简单选择排序 | 堆排序 |
| 交换排序 | 冒泡排序 | 快速排序 |
| 归并排序 | 归并排序 |
在此对每个排序方法做下总结以及实现：
一、插入类排序
1. 直接插入排序：将一个记录插入到已经排好序的有序表中
def zhijiecharu(list):
if not list:
return false
for i in range(1, len(list)):
tmp = list[i]
j = i-1
if tmp < list[j]:
while(list[j] > tmp and j >= 0):
list[j+1] = list[j]
j -= 1
list[j+1] = tmp
return list
if __name__ == '__main__':
array = [49, 38, 65, 97, 76, 13, 27, 49, 55, 4]
print(zhijiecharu(array))2. 希尔排序：为了使整个序列变得基本有序，在直接插入基础上，增加了Increment这个变量，先跳着进行一次直接插入排序，这个跳的步幅越来越小，最后一次就是1.
写代码时出错的点：
（1）temp搞不清楚是给新来的数还是下标减increment的数
（2）while里面经常忘了写and j>=0这个条件
def shell_sorted(list):
if not list:
print(False)
incremnt = len(list)
while incremnt > 1:
incremnt = incremnt // 3 + 1
# print(incremnt)
for i in range(incremnt, len(list)):
temp = list[i]
j = i - incremnt
if list[j] > temp:
while(list[j] > temp and j >= 0):
list[j+incremnt] = list[j]
j -= incremnt
list[j+incremnt] = temp
return list
if __name__ == '__main__':
array = [49, 38, 65, 97, 76, 13, 27, 49, 55, 4]
print(shell_sorted(array))二、选择排序类
1. 简单选择排序：在当前下标以后，选择最小的数，和当前下标的数作比较并且交换
def easy_select(list):
if not list:
return False
for i in range(len(list)):
min_ind = i
min_key = list[i]
for j in range(i+1,len(list)):
if list[j] < min_key:
min_key = list[j]
min_ind = j
if i!=min_ind:
temp = list[i]
list[i] = min_key
list[min_ind] = temp
return list
if __name__ == '__main__':
array = [49, 38, 65, 97, 76, 13, 27, 49, 55, 4]
print(easy_select(array))
2. 堆排序：先将整个序列排成大顶堆，将堆顶元素与序列最后一个元素互换，再对前n-1个数字排成大顶堆。
写代码时出错的点：
（1） python中下标不能直接乘以2，应该2*(i+1)-1
（2）while的最后一句有点不太清楚是写外面还是写里面
def swap(list, i, j):
temp = list[i]
list[i] = list[j]
list[j] = temp
return list
def get_heap(list, start_ind, end_ind):
j = 2 * (start_ind + 1) - 1
while(j <= end_ind ):
temp = list[start_ind]
if (j+1)<=end_ind and list[j] < list[j+1]:
j +=1
if list[j] <= temp:
break
else:
list[start_ind] = list[j]
list[j] = temp
start_ind = j
j = 2*(j+1)-1
# list[(j+1)//2-1] = temp
print(list)
def heap_sort(list):
if not list:
return False
for i in range(len(list)//2-1,-1,-1):
m = len(list)-1
get_heap(list, i, m)
for j in range(len(list)-1,-1,-1):
swap(list, 0, j)
get_heap(list, 0, j-1)
return list
if __name__ == '__main__':
array = [49, 38, 65, 97, 76, 13, 27, 49, 55, 4]
array2 = [5,1,9,3,7,4,8,6,2]
# print([i for i in range(3,-1,-1)])
print(heap_sort(array2))三、交换类排序
1. 冒泡排序：相邻两个逐个对比
def maopao(list):
if not list:
return False
for i in range(len(list) - 1):
for j in range(len(list)-2, i-1, -1):
if list[j] > list[j+1]:
temp = list[j]
list[j] = list[j+1]
list[j+1] = temp
return list
if __name__ == '__main__':
array = [9,1,5,8,3,7,4,6,2]
print(maopao(array))2. 快速排序：首先选定一个pivotkey并获取其在待排序列中的坐标Pivot，保证pivot左边所有数字均小于pivotkey，右边所有数字均大；根据pivot位置，将待排序列分成左右两个子序列，再对两个子序列进行递归来排序。（排序的交换操作实际上在获取pivot的过程中进行）
def quick_sort(list):
if not list:
return False
qsort(list, 0, len(list)-1)
return list
def get_pivot_ind(list, low, high):
# get pivot
mid = (low + high)//2
if list[low] > list[high]:
temp = list[low]
list[low] = list[high]
list[high] = temp
if list[mid] > list[high]:
temp = list[mid]
list[mid] = list[high]
list[high] = temp
if list[low] < list[mid]:
list[mid],list[low] = list[low],list[mid]
# temp = list[mid]
# list[mid] = list[low]
# list[low] = temp
temp = list[low]
while(low < high):
while(low < high and list[high] > temp):
high -= 1
list[low] = list[high]
while(low < high and list[low] < temp):
low += 1
list[high] = list[low]
list[low] = temp
return low
def qsort(list, low, high):
while (low < high):
pivotind = get_pivot_ind(list, low, high)
qsort(list, low, pivotind-1)
low = pivotind + 1
return list
if __name__ == '__main__':
array = [9,1,5,8,3,7,4,6,2]
print(quick_sort(array))
四、归并类排序