Just a complicated Quick sort implementation

// I can't tell you what it really is,
// I can only tell you what it feels like.
#include "bits/stdc++.h"
using namespace std;

int a[10000];
int iter, n;

int partition(int l, int r) {
  //   cout << "before: ";
  //   for (int i = l; i <= r; ++i) {
  //     cout << a[i] << ' ';
  //   }cout << endl;
  // cout << "pivot: " << a[l] << '\n';
  //   cout << l << ' ' << r << ' ';
  //   ++iter;
  //   if (iter>100)exit(0);
  int pivot = a[l];
  int i = l+1;
  int j = r;
  while (i < j) {
    while (i < r && a[i] < pivot) ++i;
    while (j > l && a[j] >= pivot) --j;
    if (i < j) swap(a[i], a[j]);
  }
   swap(a[l], a[j]);
   // cout << "partition: " << j << '\n';
   // cout << "after: ";
   //  for (int i = l; i <= r; ++i) {
   //    cout << a[i] << ' ';
   //  }cout << endl;
   //  cout << endl;
  return j;
}


void quick(int lo, int hi) {
  if (lo >= hi) return;
  if (lo + 1 == hi) {
    if (a[lo] > a[hi]) swap(a[lo], a[hi]);
    return;
  }
  int p = partition(lo, hi);

  quick(lo, p-1);
  quick(p+1, hi);
}

signed main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  srand(time(NULL));

  // n = rand() % 1000 + 1;
  cin >> n;

  for (int i = 0; i < n; ++i)
    cin >> a[i];
    // a[i] = rand() % 10000 + 7;

  random_shuffle(a, a+n);
  quick(0, n-1);
  // cout << n << '\n';
  for (int i = 0; i < n; ++i) {
    cout << a[i] << ' ';
  }
  // cout << endl;
  // if(!is_sorted(a, a+n)) cout << "fuck";
  assert(is_sorted(a, a+n));
  return 0;
}
// 1). Try forming/rearranging the equations if any
// 2). If problem asks to count, try counting in reverse(it can be easier sometimes)