AcWing 786. 第k个数 - AcWing[第二天](12.2)

AcWing 786. 第k个数 - AcWing

法一：

b站上的视频课学的，运用了快排的基本概念。

'''n为1000时，递归深度太大不支持'''
def quick_sort(date, left, right):
    if left < right:
        mid = partition(date, left, right)
        quick_sort(date, left, mid - 1)
        quick_sort(date, mid + 1, right)
        
def partition(date, left, right):
    tmp = date[left]
    while left < right:
        while left < right and date[right] >= tmp:
            right -= 1
        date[left] = date[right]
        while left < right and date[left] <= tmp:
            left += 1
        date[right] = date[left]
    date[left] = tmp
    return left

def main():
    l = 0
    r = n - 1
    quick_sort(data, l, r)
    
if __name__ == "__main__":
    n = int(input())
    data = [int(x) for x in range(1000)]
    main()
    print(' '.join(list(map(str, data))))

法二：

AcWing上的，通过python复刻y总的c++代码，运用了二分

def quick_sort(l, r, data):
    if l >= r:
        return
    i = l - 1
    j = r + 1
    pivot = data[(i + j) // 2]
    while i < j:
        while 1:
            i += 1
            if data[i] >= pivot:
                break
        while 1:
            j -= 1
            if data[j] <= pivot:
                break
        if i < j:
            data[i], data[j] = data[j], data[i]
    quick_sort(l, j, data)
    quick_sort(j + 1, r, data)

def main():
    l = 0
    r = n - 1
    quick_sort(l, r, data)

if __name__ == "__main__":
    n = int(input())
    data = [int(x) for x in input().split()]
    main()
    print(' '.join(list(map(str, data))))