快速排序

public static void main(String[] args) {

    int arr[] ={75,70,85,80,60,100,90};
    // 75 70 60 80 85 100 90  ==> 60 70 75 80 85 100 90
    QuickSort(arr,0,6);
    System.out.println(Arrays.toString(arr));
}

public static int [] QuickSort(int arr[],int start,int end){

if(end>start){

    int partition = partition(arr,start,end);

    QuickSort(arr,start,partition-1);
    QuickSort(arr,partition+1,end);

}

return arr;
}

public static int partition(int arr[],int start,int end){

    int prior = arr[start];
    int partition=start;
    int left = start;
    int right = end;

    while(leftleft && arr[right]>=prior ){
            right--;
        }

        while (left