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- 基本算法:
# 冒泡: https://cuijiahua.com/blog/2017/12/algorithm_1.html
它重复地走访要排序的数列,一次比较两个元素,如果他们的顺序错误就把他们交换过来。走访数列的工作是重复地进行直到没有再需要交换,也就是说该数列已经排序完成。这个算法的名字由来是因为越小的元素会经由交换慢慢“浮”到数列的顶端,故名冒泡排序。
def bubble_sort(alist):
n = len(alist)
if n ==0:
return []
for j in range(n-1):
count = 0
for i in range(n-1-j):
if alist[i] > alist[i+1]:
alist[i],alist[i+1] = alist[i+1],alist[i]
count += 1
if count == 0 :
break
return alist
插入: 其原理是通过构建一个初始的有序序列,然后从无需序列中抽取元素,插入到有序序列的相对排序位置,
def insert_sort(alist):
n = len(alist)
for j in range(1,n):
for i in range(j,0,-1):
if alist[i] < alist[i-1]
alist[i],alist[i-1] = alist[i-1],alist[i]
else:
break
快排:
def quick_sort(alist,start,end):
if start >= end:
return
mid = alist[start]
low = start
hight = end
while low < hight:
while low < hight and alist[hight] >= mid:
hight -= 1
alist[low] = alist[hight]
while low < hight and alist[low] < mid:
low += 1
alist[hight] = alist[low]
alist[low] = mid
quick_sort(alist,first,low-1)
quick_sort(alist,low+1,end)
选择:
def selection_sort(alist):
"""选择排序"""
n = len(alist)
for i in range(n-1):
min_index = i # [0,1,2,3,n-2] 遍历到倒数第二个元素
for j in range(i+1,n):
if alist[j] < alist[min_index]:
min_index = j
# 如果选择出的数据不在正确位置,进行交换
if min_index != i:
alist[i],alist[min_index] = alist[min_index],alist[i]
li = [23,44,32,34,34,23,52,12,34,11]
selection_sort(li)
print(li)
# n**2
# 不稳定