照时空小涵的题解自己敲的，为什么会超时TAT

#include<iostream>
using namespace std;
int a[5000000];
int quickSort(int low, int high)
{
	int mid = a[low];
	while (low < high)
	{
		while (a[high] >= mid && low < high)high--;
		if(low<high)a[low++] = a[high];
		while (a[low] <= mid&&low < high)low++;
		if(low<high)a[high--] = a[low];
	}
	a[low] = mid;
	return low;
}
void find(int low, int high, int k)
{
	int index = quickSort(low, high);
	if (index == k)
	{
		cout<<a[index];
	}
	else if (index > k)
	{
		find(low, index - 1, k);
	}
	else
		find(index + 1, high, k);
}
int main()
{
	int n, k;
	cin >> n >> k;
	for (int i = 0;i < n;i++)
	{
		cin >> a[i];
	}
	find(0, n-1, k);
	return 0;
}