排序

一、快速排序

def quick_sort(arry):
    if len(arry)<=1:
        return arry
    target = arry[0]
    left, right = [], []
    i = 1
    while i < len(arry):
        if arry[i] <= target:
            left.append(arry[i])
        else:
            right.append(arry[i])
        i += 1
    return quick_sort(left) + [target] + quick_sort(right)

def get_index(nums,begin,end):
    i,j = begin,end-1
    while i<j:
        while i<j and nums[i]<=nums[end]:
            i+=1
        while i<j and nums[j]>=nums[end]:
            j-=1
        nums[i],nums[j] = nums[j],nums[i]
    if nums[end]<nums[i]:
        nums[i],nums[end] = nums[end],nums[i]
    return i

def quick_sort(nums,begin,end):
    if begin<end:
        index = get_index(nums,begin,end)
        quick_sort(nums,begin,index)
        quick_sort(nums,index+1,end)

二、归并排序

def merge(a,b):
    c = []
    i,j=0,0
    while i<len(a) and j<len(b):
        if a[i]<=b[j]:
            c.append(a[i])
            i+=1
        else:
            c.append(b[j])
            j+=1
    if i==len(a):
        c.extend(b[j:])
    if j==len(b):
        c.extend(a[i:])
    return c
def merge_sort(arry):
    if len(arry)<=1:
        return arry
    mid = len(arry)//2
    left = merge_sort(arry[:mid])
    right = merge_sort(arry[mid:])

    return merge(left,right)