sort an array using quicksort

#include <iostream>
using namespace std;

void mquicksort(int A[], int l, int u)
{
    if(l>=u)
        return;
        
    int m=l;
    
    for(int i=l+1; i<u; i++)
    {
        if(A[i] < A[l])
        {
            int t=A[i];
            A[i] = A[m+1];
            A[m+1]=t;
            m++;
        }
    }

    int t=A[l];
    A[l] = A[m];
    A[m]=t;

    mquicksort(A, l, m-1);
    mquicksort(A, m+1, u);
}

int main() {
    // your code goes here
    int A[20];
    int n;
    cout << "enter number of elements(<=20) to be sorted:";
    cin >> n;
    cout << "\nenter " << n << " elements now\n";
    for(int i=0;i<n;i++)
    {
        cin >> A[i];
    }
    mquicksort(A, 0, n);
    
    cout << "\n\nsorted numbers: ";
    for(int i=0;i<n;i++)
    {
        cout << A[i] << " ";
    }

    return 0;
}