Python版排序算法整理

前言

经典的排序算法,用Python来实现,可以非常简洁。

快速排序

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# -*- coding:utf-8 -*-
class Solution:
def GetLeastNumbers_Solution(self, tinput, k):
# write code here
def quick_sort(lst):
if not lst:
return []
pivot = lst[0]
left = quick_sort([x for x in lst[1: ] if x < pivot])
right = quick_sort([x for x in lst[1: ] if x >= pivot])
return left + [pivot] + right

if tinput == [] or k > len(tinput):
return []
tinput = quick_sort(tinput)
return tinput[: k]

归并排序

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# -*- coding:utf-8 -*-
class Solution:
def GetLeastNumbers_Solution(self, tinput, k):
# write code here
def merge_sort(lst):
if len(lst) <= 1:
return lst
mid = len(lst) // 2
left = merge_sort(lst[: mid])
right = merge_sort(lst[mid:])
return merge(left, right)
def merge(left, right):
l, r, res = 0, 0, []
while l < len(left) and r < len(right):
if left[l] <= right[r]:
res.append(left[l])
l += 1
else:
res.append(right[r])
r += 1
res += left[l:]
res += right[r:]
return res
if tinput == [] or k > len(tinput):
return []
tinput = merge_sort(tinput)
return tinput[: k]

堆排序

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# -*- coding:utf-8 -*-
class Solution:
def GetLeastNumbers_Solution(self, tinput, k):
# write code here
def siftup(lst, temp, begin, end):
if lst == []:
return []
i, j = begin, begin * 2 + 1
while j < end:
if j + 1 < end and lst[j + 1] > lst[j]:
j += 1
elif temp > lst[j]:
break
else:
lst[i] = lst[j]
i, j = j, 2 * j + 1
lst[i] = temp

def heap_sort(lst):
if lst == []:
return []
end = len(lst)
for i in range((end // 2) - 1, -1, -1):
siftup(lst, lst[i], i, end)
for i in range(end - 1, 0, -1):
temp = lst[i]
lst[i] = lst[0]
siftup(lst, temp, 0, i)
return lst

if tinput == [] or k > len(tinput):
return []
tinput = heap_sort(tinput)
return tinput[: k]

冒泡排序

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# -*- coding:utf-8 -*-
class Solution:
def GetLeastNumbers_Solution(self, tinput, k):
# write code here
def bubble_sort(lst):
if lst == []:
return []
for i in range(len(lst)):
for j in range(1, len(lst) - i):
if lst[j-1] > lst[j]:
lst[j-1], lst[j] = lst[j], lst[j-1]
return lst

if tinput == [] or k > len(tinput):
return []
tinput = bubble_sort(tinput)
return tinput[: k]

选择排序

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# -*- coding:utf-8 -*-
class Solution:
def GetLeastNumbers_Solution(self, tinput, k):
# write code here
def select_sort(lst):
if lst == []:
return []
for i in range(len(lst)-1):
smallest = i
for j in range(i, len(lst)):
if lst[j] < lst[smallest]:
smallest = j
lst[i], lst[smallest] = lst[smallest], lst[i]

return lst

if tinput == [] or k > len(tinput):
return []
tinput = select_sort(tinput)
return tinput[: k]

插入排序

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# -*- coding:utf-8 -*-
class Solution:
def GetLeastNumbers_Solution(self, tinput, k):
# write code here
def Insert_sort(lst):
if lst == []:
return []
for i in range(1, len(lst)):
temp = lst[i]
j = i
while j > 0 and temp < lst[j - 1]:
lst[j] = lst[j - 1]
j -= 1
lst[j] = temp
return lst

if tinput == [] or k > len(tinput):
return []
tinput = Insert_sort(tinput)
return tinput[: k]