各种常用算法

import random
import time
import sys
sys.setrecursionlimit(10000)


def cal_time(func):
    def wrapper(*args, **kwargs):
        start = time.time()
        res = func(*args, **kwargs)
        end = time.time()
        print('%s 执行的时间是 %s' % (func.__name__, end-start))
        return res
    return wrapper



# 冒泡排序
# 时间复杂度: O(n^2)
# 空间复杂度: O(1)
@cal_time
def bubble_sort(li):
    for i in range(len(li)-1):
        flag = False
        for j in range(len(li)-i-1):
            if li[j+1] < li[j]:
                li[j+1], li[j] = li[j], li[j+1]
                flag = True
        if not flag:
            return

# 选择排序
# 时间复杂度: O(n^2)
# 空间复杂度: O(1)
@cal_time
def select_sort(li):
    for i in range(len(li)-1):
        minLoc = i # minLoc = 0
        for j in range(i+1,len(li)):
            if li[j] < li[minLoc]: # li[2] < li[0]
                li[j], li[minLoc] = li[minLoc], li[j]

# 插入排序
# 时间复杂度: O(n^2)
# 空间复杂度: O(1)
@cal_time
def insert_sort(li):
    for i in range(1,len(li)):
        tmp = li[i]  # 第一次 :tmp = li[1] = 7    第二次:  tmp = li[2] = 4
        j = i - 1   # 第一次:j = 1 - 1 = 0 => li[j] = li[0] = 5 第二次: j = i - 1 = 1 ===> li[1] = 7
        while j >= 0 and tmp < li[j] : # 第一次: 7 < 5  第二次:  4 < 7
            li[j+1] = li[j]   # li[2] = li[1] = 7  ===> li[2] = 7  [5,7,7,6,3,1,2,9,8] | li[1] = li[0] = 5 [5,5,7,6,3,1,2,9,8]
            j = j - 1   # 第二次: j = 0   4 < li[0] === > 4 < 5
        li[j+1] = tmp    # li[0] = tmp = 4  ==> li[0] = 4  ===> [4,5,6,7,3,1,2,9,8]


# 快速排序
# 时间复杂度: nlogn
# 空间复杂度: O(1)
# [5,7,4,6,3,1,2,9,8]
def patition(li, left, right):
    tmp = li[left] # 5
    while left < right:
        while left < right and tmp <= li[right]:
            right = right - 1
        li[left] = li[right] # [2,7,4,6,3,1,2,9,8]   # [2,1,4,6,3,1,2,9,8]

        while left < right and tmp >= li[left]:
            left = left + 1
        li[right] = li[left] # [2,7,4,6,3,1,7,9,8]
    li[left] = tmp
    return left


def quick_sort(li, left, right):
    if left < right:
        mid = patition(li, left, right)
        quick_sort(li, left, mid-1)
        quick_sort(li, mid+1, right)

@cal_time
def quick(li, left, right):
    quick_sort(li, left, right)



def merge(li, left, mid, right):
    i = left
    j = mid + 1
    ltmp = []
    while i <= mid and j <= right:
        if li[i] < li[j]:
            ltmp.append(li[i])
            i = i + 1
        else:
            ltmp.append(li[j])
            j = j + 1
    while i <= mid:
        ltmp.append(li[i])
        i = i + 1

    while j <= right:
        ltmp.append(li[j])
        j = j + 1

    li[left:right+1] = ltmp

# 归并算法
# 时间复杂度: O(nlogn)
# 空间复杂度: O(n)
def merge_sort(li, left, right):

    if left < right:
        mid = (left + right) // 2
        merge_sort(li, left, mid)
        merge_sort(li, mid+1, right)
        print('归并之前:', li[left:right+1])
        merge(li, left, mid, right)
        print('归并之后:', li[left:right+1])

# 计数排序
def count_sort(li):
    ltmp = [0 for i in range(11)]

    print(ltmp)

    for x in li:
        ltmp[x] += 1
    #ltmp = [0, 0, 1, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0]
    print(ltmp)
    li.clear()
    for index, val in enumerate(ltmp):
        print(index, val)
        for v in range(val):
            li.append(index)




li = [10,4,6,3,8,2,5,7]
count_sort(li)
print(li)

# quick_sort(li, 0, len(li)-1)
# print(li)

# li = [1,2,3,4,5,6,7,8,9]

# li = [i for i in range(random.randint(0,10000))]
# li = [random.randint(0,1000) for i in range(100000)]
# quick(li, 0, len(li)-1)
#
# li = [random.randint(0,1000) for i in range(100000)]
# bubble_sort(li)
#
# li = [random.randint(0,1000) for i in range(100000)]
# insert_sort(li)
#
# li = [random.randint(0,1000) for i in range(100000)]
# select_sort(li)

# print(li)