#include <vector> class Solution { private: void quick_sort(vector<int>& a, int l, int r){ if(l>=r) return; int i=l-1,j=r+1,x=a[(i+j)>>1]; while(i<j){ do i++; while (a[i]<x); do j--; while (a[j]>x); if(i<j) swap(a[i],a[j]); } quick_sort(a, l, j); quick_sort(a, j+...