python16_day39【算法】

复习：

　　1.递归

• 调用自身
• 结束条件

一、冒泡算法

def bubble_sort(numbs):
    for i in range(len(numbs)-1):       # 这个循环负责设置冒泡排序进行的次数。
        for j in range(len(numbs)-i-1): # j为列表索引， -1为了报错IndexError: list index out of range
            if numbs[j] > numbs[j+1]:
                numbs[j], numbs[j+1] = numbs[j+1], numbs[j]
    return numbs
nums = [5,2,45,6,8,2,1]

print(bubble_sort(nums))

二、冒泡优化版

def bubble_sort(numbs):
    for i in range(len(numbs)-1):       # 这个循环负责设置冒泡排序进行的次数。
        exchange = False
        for j in range(len(numbs)-i-1): # j为列表索引， -1为了报错IndexError: list index out of range
            if numbs[j] > numbs[j+1]:
                numbs[j], numbs[j+1] = numbs[j+1], numbs[j]
                exchange = True
        if not exchange:
            break
    return numbs
nums = [5,2,45,6,8,2,1]

print(bubble_sort(nums))

bubble_sort

三、快排

import random
import time

def quick_sort_(data, left, right):
    if left < right:
        mid = partition(data, left, right)
        quick_sort_(data, left, mid - 1)
        quick_sort_(data, mid + 1, right)

def partition(data, left, right):
    tmp = data[left]        # 拿到最左边的数
    while left < right:     # 左右不碰的时候一直走。
        while left < right and data[right] >= tmp:  # 从右边找
            right -= 1  # 如果右边的大，右边向左移
        data[left] = data[right]  # 如果右边的小，移到左边去。
        while left < right and data[left] <= tmp:   # 从左边找
            left += 1
        data[right] = data[left]
    data[left] = tmp  # 左右碰上了，就把TMP放回来
    return left     # 返回mid


def quick_sort(data):
    return quick_sort_(data, 0, len(data)-1)

data = list(range(10000))
random.shuffle(data)
quick_sort(data)