快排java代碼

定一個基准位，遞歸左右兩邊排序。

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);
        }
    }