排序之快排

package sort;

import java.util.Arrays;

/**
 * Created by gch on 2017-08-15.
 */
public class QuickSort {
    public static void main(String[] args) {
        int[] arr = {9,8,7,6,4,4,3,2,1};
        quickSort(arr,0,arr.length-1);
        System.out.print(Arrays.toString(arr));
    }

    public static void quickSort(int[] arr,int low,int high){
        if(low > high){
            return;
        }
        int mid = partition(arr,low,high);
        quickSort(arr,low,mid-1);
        quickSort(arr,mid+1,high);
    }

    public static int partition(int[] arr,int low,int high){
        int key = arr[low];
        while(low < high){
            while(high > low && arr[high] >= key){
                high--;
            }
            arr[low] = arr[high];
            while (low < high && arr[low] < key){
                low++;
            }
            arr[high] = arr[low];
        }
        arr[low] = key;
        return low;
    }
}