python实现排序算法解析
本文实例为大家分享了python实现排序算法的具体代码，供大家参考，具体内容如下
一、冒泡排序
def bububle_sort(alist):
"""冒泡排序(稳定|n^2m)"""
n = len(alist)
for j in range(n-1):
count = 0
for i in range(0,n-1-j):
if alist[i]>alist[i+1]:
count +=1
alist[i], alist[i+1] = alist[i+1], alist[i]
if count==0:
return
二、选择排序
def select_sort(alist):
"""选择排序(不稳定|n^2)"""
n = len(alist)
for j in range(n-1):
min_index = j
for i in range(j+1,n):
if alist[min_index] > alist[i]:
min_index = i
alist[j], alist[min_index] = alist[min_index], alist[j]
三、插入排序
def insert_sort(alist):
"""插入排序(稳定|n^2)"""
n = len(alist)
for j in range(1,n):
i = j
while i>0:
if alist[i] < alist[i-1]:
alist[i], alist[i-1] = alist[i-1], alist[i]
i -= 1
else:
break
四、希尔排序
def shell_sort(alist):
"""希尔排序(不稳定|n^2)"""
n = len(alist)
gap = n//2
while gap>=1:
for j in range(gap,n):
i=j
while i>0:
if alist[i]<alist[i-gap]:
alist[i], alist[i-gap] = alist[i-gap], alist[i]
i -= gap
else:
break
gap //=2
五、快速排序
def quick_sort(alist, first, last):
"""快速排序(不稳定|n^2)"""
if first >= last:
return
mid_value = alist[first]
low = first
high = last
while low < high:
#high左移
while low <high and alist[high] >= mid_value:
high -= 1
alist[low] = alist[high]
#low右移
while low < high and alist[low] < mid_value:
low += 1
alist[high] =alist[low]
#从循环退出时，low=high
alist[low] = mid_value
#对low左边的列表执行快速排序
quick_sort(alist, first, low-1)
#对low右边的列表执行快速排序
quick_sort(alist, low+1, last)
六、归并排序
def merge_sort(alist):
"""归并排序(稳定|nlgn)"""
n = len(alist)
if n <= 1:
return alist
mid = n//2
#left 采用归并排序后形成新的有序列表
left_li = merge_sort(alist[:mid])
#right 采用归并排序后形成新的有序列表
right_li = merge_sort(alist[mid:])
#merge(left, right) 将两个有序的子序列合并为一个新的整体
left_pointer, right_pointer = 0, 0
result = []
while left_pointer < len(left_li) and right_pointer<len(right_li):
if left_li[left_pointer] < right_li[right_pointer]:
result.append(left_li[left_pointer])
left_pointer += 1
else:
result.append(right_li[right_pointer])
right_pointer += 1
result += left_li[left_pointer:]
result += right_li[right_pointer:]
return result
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持【听图阁-专注于Python设计】。
