python笔记

用python实现冒泡排序 选择排序 插入排序

  • 冒泡法排序

    第一个循环倒序,相邻两个元素比较大小然后交换.第一次将最大的一个逐渐排序到列表最后一个位置.
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from __future__ import print_function, unicode_literals, division
arry = [16, 134, 15, 1, 78, 10, 9]
def bubble_sort(arry):
    for i in range(len(arry) - 1, 0, -1):
        for j in range(i):
            if arry[j] > arry[j + 1]:
                arry[j], arry[j + 1] = arry[j + 1], arry[j]
if __name__ == "__main__":
    bubble_sort(arry)
    print (arry)
[1, 9, 10, 15, 16, 78, 134]

  • 选择法排序

    第一个元素和后面所有元素对比,找到最小的一个,然后交换.
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from __future__ import print_function, unicode_literals, division
arry = [16, 134, 15, 1, 78, 10, 9]
def select_sort(arry):
    length = len(arry)
    for i in range(length - 1):
        sort_index = i
        for j in range(i, length):
            if arry[j] > arry[sort_index]:
                sort_index = j
        arry[sort_index], arry[i] = arry[i], arry[sort_index]
if __name__ == "__main__":
    select_sort(arry)
    print(arry)
[1, 9, 10, 15, 16, 78, 134]

  • 插入排序

最开始以第一个元素为准,第二个元素与第一个比较,排序.第三个与前两个比较然后排序.以此类推.

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rom __future__ import print_function, unicode_literals, division
arry = [17, 23, 20, 14, 12, 25, 1, 20, 81, 14, 11, 12]
def select_sort(arry):
    length = len(arry)
    for i in range(length - 1):
        sort_index = i
        for j in range(i, length):
            if arry[j] < arry[sort_index]:
                sort_index = j
        if sort_index != i:
            arry[sort_index], arry[i] = arry[i], arry[sort_index]
if __name__ == "__main__":
    select_sort(arry)
    print(arry)

`

[1, 11, 12, 12, 14, 14, 17, 20, 20, 23, 25, 81]