Python代码实现归并排序

Posted 2021-02-19 代码改变世界！

一、归并排序

　　先通过递归将列表元素分开，然后通过合并比较大小进行排序。

二、上代码

def merge(li, low, mid, high):
    """
    归并排序
    :param li:参数列表
    :param low: 列表最左边
    :param mid: 列表中间的
    :param high: 列表最右边
    :return:
    """
    i = low
    j = mid + 1
    ltmp = []
    while i <= mid and j <= high:
        if li[i] < li[j]:
            ltmp.append(li[i])
            i += 1
        else:
            ltmp.append(li[j])
            j += 1
    while i <= mid:
        ltmp.append(li[i])
        i += 1
    while j <= high:
        ltmp.append(li[j])
        j += 1
    li[low:high+1] = ltmp


li = [2, 4, 5, 6, 1, 3, 7, 8, 9]
# merge(li,0,3,8)
# print(li)


def merge_sort(li, low, high):
    if low < high:
        mid = (low + high) // 2
        merge_sort(li, low, mid)
        merge_sort(li, mid+1, high)
        merge(li, low, mid, high)


merge_sort(li, 0, 8)
print(li)