python_基础算法

一、二分查找

def binary(binary_para, search):
    bi = int(len(binary_para)/2)
    if search == binary_para[0]:
        print('数存在，并存在在列表第一位')
    elif len(binary_para)>1:
        if binary_para[bi] > search:
            print('分段值（前）：',binary_para[bi])
            binary(binary_para[:bi],search)
        elif binary_para[bi] < search:
            print('分段值（后）：',binary_para[bi])
            binary(binary_para[bi:],search)
        else:
            print('你寻找的数存在列表里')
    else:
        print('列表里不存在你寻找的数')

if __name__ == '__main__':
    li = list(range(8,30000,10))
    binary(li, 12138)

二、冒泡排序

def bub_sort(sort_list):
    for i in range(len(sort_list)-2):
        for j in range(len(sort_list)-i-1):
            if sort_list[j]>sort_list[j+1]:
                temp = sort_list[j+1]
                sort_list[j+1] = sort_list[j]
                sort_list[j] = temp


if __name__ == '__main__':
    li = [65, 1, 45, 77, 3, 9, 43, 23, 7, 53, 213, 10]
    bub_sort(li)
    print(li)

三、选择排序

def select_sort(list_sort):
    for i in range(len(list_sort)):
        min_index = i
        for j in range(i, len(list_sort)):
            if list_sort[min_index] > list_sort[j]:
                min_index = j
        temp = list_sort[i]
        list_sort[i] = list_sort[min_index]
        list_sort[min_index]=temp

if __name__ == '__main__':
    li = [65, 1, 45, 77, 3, 9, 43, 23, 7, 53, 213, 10]
    select_sort(li)
    print(li)

四、插入排序

def insert_sort(sort_list):
    for i in range(1,len(sort_list)):
        insert_index = i    # 索引当做类似指针的使用
        insert_value = sort_list[i]    # 把要插入的值存下来，以免后面被覆盖
        while insert_index > 0 and insert_value < sort_list[insert_index-1]:
            sort_list[insert_index] = sort_list[insert_index-1]
            insert_index -=1
        sort_list[insert_index] = insert_value

if __name__ == '__main__':
    li = [65, 1, 45, 77, 3, 9, 43, 23, 7, 53, 213, 10]
    insert_sort(li)
    print(li)
    

五、快速排序

图片来源：https://www.jianshu.com/p/5f38dd54b11f

def quick_sort(list_sort,start,end):
    if start >= end:
        return
    start_index = list_sort[start]
    left_flag = start
    right_flag = end

    while left_flag < right_flag:

        while left_flag < right_flag and start_index <= list_sort[right_flag]:
            right_flag -=1
        list_sort[left_flag] = list_sort[right_flag]

        while left_flag < right_flag and start_index >= list_sort[left_flag]:
            left_flag += 1
        list_sort[right_flag] = list_sort[left_flag]

    list_sort[left_flag] = start_index
    quick(list_sort, start, end, left_flag)     # 递归调用

def quick(list_sort,start,end,left_flag):
    quick_sort(list_sort,start,left_flag-1)
    quick_sort(list_sort,left_flag+1,end)

if __name__ == '__main__':
    li = [64, 77, 67, 8, 6, 84, 55, 20, 43, 67, 67]
    quick_sort(li, 0, len(li) - 1)
    print(li)