package homework.c260717;


import java.util.Arrays;
import java.util.Random;

/**
 * @author WanJl
 * @version 1.0
 * @title Demo_08
 * @description 题目8：数组随机打乱
 * @create 2026/7/21
 */
public class Demo_08 {
    public static void shuffleArray(int[] arr) {
        Random ran = new Random();
        // 从后往前遍历，实现 Fisher-Yates 洗牌
        for (int i = arr.length-1; i>1 ; i--) {
            int j=ran.nextInt(i+1);
                int t=arr[i];
                arr[i]=arr[j];
                arr[j]=t;
        }
    }

    public static void main(String[] args) {
        int[] arr = {1, 2, 3, 4, 5, 6, 7};
        System.out.println("打乱前：" + Arrays.toString(arr));
        shuffleArray(arr);
        System.out.println("打乱后：" + Arrays.toString(arr));
    }
}