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java语言实现快速排序的两种方式

2024-07-03 21:27:41   227人阅读

方法一：

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public class QuickSortExp1{
    public static void main(String[] args){
        int[] sortArray = new int[]{5,7,4,2,9,8,3,6};
        System.out.println("before sorting ,the numbers are:");
        show(sortArray);
        quickSort(sortArray,0,sortArray.length-1);
        System.out.println("after sorting,the numbers are:");
        show(sortArray);
    }
    public static void quickSort(int[] intArray,int left,int right){
        if(left<right){
            int partValue =http://www.mamicode.com/ intArray[left];
            int low = left;
            int high = right;
            while(low < high){
                while(low <high && intArray[high]>partValue){
                    high--;
                }
                intArray[low] = intArray[high];
                while(low <high && intArray[low] <partValue){
                    low++;
                }
                intArray[high] = intArray[low];
            }
            intArray[low] = partValue;
            quickSort(intArray,left,low-1);
            quickSort(intArray,low+1,right);
        }
    }
    public static void show(int[] intArray){
        for(int i=0;i<intArray.length;i++){
            System.out.print(intArray[i]+"\t");
        }
        System.out.println();
    }
}

　　

方法二：

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import java.util.*;
public class QuickSortExp2{
    public static void main(String[] args){
        List<Integer> sortList = new ArrayList<Integer>();
        sortList.add(5);
        sortList.add(7);
        sortList.add(4);
        sortList.add(2);
        sortList.add(9);
        sortList.add(8);
        sortList.add(3);
        sortList.add(6);       
        System.out.println("before sorting ,the numbers are:");
        show(sortList);
        quickSort(sortList);
        System.out.println("after sorting,the numbers are:");
        show(sortList);
    }
    public static void quickSort(List<Integer> sortList){    
        if(sortList.size() <= 1){
            return;
        } else if(sortList.size() == 2){
            if(sortList.get(0)>sortList.get(1)){
                int temp = sortList.get(0);
                sortList.set(0,sortList.get(1));
                sortList.set(1,temp);
            }
        } else{    
            List<Integer> leftList = new ArrayList<Integer>();
            List<Integer> rightList = new ArrayList<Integer>();
            int partValue = http://www.mamicode.com/sortList.get(0);       
            for(int i=1;i<sortList.size();i++){
                if(sortList.get(i)< partValue){
                    leftList.add(sortList.get(i));
                } else{
                    rightList.add(sortList.get(i));
                }
            }  
            quickSort(leftList);
            quickSort(rightList);
             
            sortList.clear();
            sortList.addAll(leftList);
            sortList.add(partValue);
            sortList.addAll(rightList);
            leftList.clear();
            rightList.clear();         
        }          
    }
    public static void show(List<Integer> sortList){
        for(Integer i:sortList){
            System.out.print(i+"\t");
        }
        System.out.println();
    }
}

　　

 


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