定一个基准位，递归左右两边排序。

public void fun(){        int arr[] = {2,3,4,5,6,7,822,3,4,5,8,6,5,4,2,1};        //System.out.println(qsort(arr,0,(arr.length)-1));        dofun(arr,0,(arr.length)-1);        for(int i = 0 ; i < arr.length ; i ++){            System.out.println(arr[i]);        }    }    private int  qsort(int arr[],int left ,int right) {        int begin_num = arr[left],i = left,j = right;        while(i != j){            while(arr[j] >= begin_num && i!=j){                j--;            }            arr[i] = arr[j];            while(arr[i] < begin_num && i!=j){                i++;            }            arr[j] = arr[i];        }        arr[i] = begin_num;        return i;     }    private void dofun(int arr[],int left,int right) {        if(left < right){            int mid = qsort(arr,left,right);            dofun(arr, left, mid);dofun(arr, mid+1, right);        }    }