排序算法的Python实现

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冒泡排序

def bubble_sort(l):
    n = len(l)
    for i in range(n):
        for j in range(i+1, n):
            if l[i] > l[j]:
                l[i], l[j] = l[j], l[i]
    return l

插入排序

def insert_sort(l):
    n = len(l)
    for i in range(1, n):
        key = l[i]
        j = i-1
        while j >= 0:
            if l[j] > key:
                l[j], l[j+1] = key, l[j]
            j -= 1
    return l

直接选择排序

def select_sort(l):
    n = len(l)
    for i in range(n):
        min = i
        for j in range(i+1, n):
            if l[min] > l[j]:
                min = j
        l[min], l[i] = l[i], l[min]
    return l

快速排序

def quick_sort(l, low, high):
    i = low
    j = high
    if i >= j:
        return l
    key = l[i]
    while i < j:
        while i < j and l[j] >= key:#从右往左，找到小于key的j
            j -= 1
        l[i] = l[j]#交换l[i]和l[j]
        while i < j and l[i] <= key:#从左往右，找到大于key的i
            i += 1
        l[j] = l[i]#交换l[j]和l[i]
    l[i] = key#退出时，i==j；将key放在l[i]的位置
    quick_sort(l, low, i-1)#调用递归
    quick_sort(l, j+1, high)
    return l