快排模板

#include<iostream>
using namespace std;
int a[100005];
int n;
void recur(int a[], int left, int right)
{
  if (left >= right)
    return;
  int pivot = a[(left + right) / 2];
  int temp = (left + right) / 2;
  int L = left, R = right;
  while (L < R)
  {
    while (a[R] >= pivot && R > temp)
      R--;
    if (R > temp)
    {
      a[temp] = a[R];
      temp = R;
    }
    //cout << L << " " << R << endl;
    /*for (int i = 0; i < 30; i++)
      if(i!=temp)
      cout << a[i] << ' ';
      else cout << '@'<<' ';
    cout << endl;*/
    //cout << temp << endl;
    while (a[L] <= pivot && L < temp)
      L++;
    if (L < temp)
    {
      a[temp] = a[L];
      temp = L;
    }
    //cout << L << " " << R << endl;
    /*for (int i = 0; i < 30; i++)
      if(i!=temp)
      cout << a[i] << ' ';
      else cout << '@'<<' ';
    cout << endl;*/
    //cout << temp << endl;
    if (L >= R)
    {
      a[temp] = pivot;
      break;
    }
  }
  //cout << left << ' ' << temp - 1 << endl;
  recur(a, left, temp - 1);
  //cout << temp + 1 << ' ' << right<< endl;
  recur(a, temp + 1, right);
}
int main()
{
  cin >> n;
  for (int i = 0; i < n; i++)
    cin >> a[i];
  recur(a, 0, n - 1);
  for (int i = 0; i < n - 1; i++)
    cout << a[i] << ' ';
  cout << a[n - 1];
  cout << endl;
  return 0;
}