Java学习笔记（8）：排序（Array.sort()，冒泡，快排）

一：冒泡排序

public class 排序 {
    
    
    public static void main(String[] args) {
    
    
        int[] array = new int[1000];
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        for (int i = 0; i < n; i++) {
    
    
            array[i] = sc.nextInt();
        }
        for (int i = 1; i < n - 1; i++) {
    
    
            for (int j = 0; j < n - i; j++) {
    
    
                if (array[j] > array[j + 1]) {
    
    
                    int temp = array[j];
                    array[j] = array[j + 1];
                    array[j + 1] = temp;
                }
            }
        }
        for (int i = 0; i < n; i++) {
    
    
            if (i < n - 1)
                System.out.print(array[i] + ",");
            else
                System.out.print(array[i]);
        }
    }
}

二.利用Arrays进行排序

Arrays.sort(数组名，起始位置，终止位置)

public static void main(String[] args) {
    
    
        int[] array = new int[1000];
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        for (int i = 0; i < n; i++) {
    
    
            array[i] = sc.nextInt();
        }
        Arrays.sort(array,0,n);
        for(int i=0;i<n;i++)
        {
    
    
            System.out.println(array[i]+" ");
        }
   }

利用Array.sort()排列，Array.toString()输出

 public static void main(String[] args) {
    
    
        int[] array = new int[1000];
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] a = new int[n];
        //因为Array.sort(数组名)默认从最初位置排到最后一位，所有长度应定为n
        for (int i = 0; i < n; i++) {
    
    
            array[i] = sc.nextInt();
            a[i] = array[i];
        }
        Arrays.sort(a);
        //out.println(Arrays.toString(a)直接输出a中全部元素
        System.out.println(Arrays.toString(a));
   }

三.快速排序

import java.util.Scanner;

public class QuickSort {
    
    
    public static void main(String[] args) {
    
    
        int [] num = new int[1000];
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        for (int i = 0; i < n; i++) {
    
    
            num[i] = sc.nextInt();
        }
       QuickSort(num,0,n-1);
        for(int i =0;i<n;i++)
        {
    
    
            System.out.print(num[i]+"   ");
        }
    }

    private static void QuickSort(int[] num, int left, int right) {
    
    

        if(left>=right) {
    
    
            return;
        }

        int key=num[left];

        int i=left;
        int j=right;
        while(i<j){
    
    

            while(num[j]>=key && i<j){
    
    
                j--;
            }

            while(num[i]<=key && i<j){
    
    
                i++;
            }

            if(i<j){
    
    
                int temp=num[i];
                num[i]=num[j];
                num[j]=temp;
            }
        }
        num[left]=num[i];
        num[i]=key;
        QuickSort(num,left,i-1);
        QuickSort(num,i+1,right);
    }
}