自己整理的算法 快速排序

Posted 2020-08-07 小竹子kisty

package sort;

public class QuickSort {
	public static void quickSort(int[] list){
		quickSort(list,0,list.length-1);
		}
	//注意这里是private
	private static void quickSort(int[] list,int first ,int last){
		//这里有一个if条件 别忘了
		if(last>first){
		int pivotIndex = partition(list, first, last);
		quickSort(list,first,pivotIndex-1);//这里是first和pivotIndex-1
		quickSort(list,pivotIndex+1,last);//这里是pivoeIndex+1
		}
		}
	//注意这里是的返回值是int
	private static int partition(int[] list,int first,int last){
		int pivot = list[first];
		int low = first+1;
		int high = last;
		
	while(low<high){
		while(low<= high&& list[low]<=pivot)
			low++;
		while(low<=high&&list[high]>pivot)
			high--;
		if(high>low){  //这里面要注意的是比较的是下标而不是数组值 ，因为此时数组值就是hign的比low的小了
			int temp= list[high];  //自己连交换条件都写错了
     		list[high] = list[low];
			list[low]=temp;
			
		}
		
	}
	
	while(high>first&&list[high]>=pivot) //注意这里面是大于等于pivot
		high--;
	if(pivot>list[high])
	{   list[first]=list[high];
		list[high]=pivot;
		return high;
	}
	else return first;
		
	}

	
public static void main(String[] args){
		int[] list = {2,3,2,5,6,1,3,14,12};
		quickSort(list);
		for(int i=0;i<list.length;i++)
		System.out.print(list[i]+" ");

}
}