我这是慢排QAQ，3.2s，求怎么改

#include <iostream>
#include <algorithm>
using namespace std;
int arr[100001];
void quicksort(int a, int b)
{
	if (a >= b) return;
	int i, j, temp;
	temp = arr[a];
	i = a; j = b;
	while (i != j)
	{
		while (arr[j] >= temp && j > i)
		{
			j--;
		}
		while (arr[i] <= temp && i < j) {
			i++;
		}
		if (i < j)
		{
			swap(arr[i], arr[j]);
		}
	}
	arr[a] = arr[i];
	arr[i] = temp;
	quicksort(a, i - 1);
	quicksort(i + 1, b);
}
int main()
{
	int n;
	cin >> n;
	for (int i = 1; i <= n; i++)
	{
		cin >> arr[i];
	}
	quicksort(1, n);
	for (int i = 1; i <= n; i++)
	{
		cout << arr[i]<<" ";
	}
	return 0;
}