抢红包

抢红包:

一个大V直播发起了抢红包活动,分别有:9,666,188,520,99999五个红包.请模拟粉丝抽奖,按照先来先得,随机抽取,抽完即止,注意:一个红包只能被抽一次,先抽或后抽哪一个红包都是随机的,示例如下(不一定是下面的顺序):

*将抽奖后的数组位置往前移,最后一位补0

public static void main(String[] args) {
    int[] arr = {9, 666, 188, 520, 99999};
    for (int i = 0; i < arr.length; i++) {
        Random r = new Random();
        System.out.print("按任意键完成抽奖:");
        Scanner sc = new Scanner(System.in);
        String key = sc.nextLine();
        int index = r.nextInt(arr.length - i);
        System.out.println("恭喜您抽中了" + arr[index]);
        if (arr.length - 1 == i) {
            System.out.println("活动结束....");
            break;
        }
        getArrayByIndex(arr, index);
    }
}

public static void getArrayByIndex(int[] arr, int index) {
    for (int i = 0; i < arr.length - 1; i++) {
        if (i >= index) {
            arr[i] = arr[i + 1];
        }
    }
    arr[arr.length - 1] = 0;
}  

*将抽奖后的剩余的元素组成新数组

public static void main(String[] args) {
    int[] arr = {9, 666, 188, 520, 99999};
    Random r = new Random();
    Scanner sc = new Scanner(System.in);
    for (int i = 0; i < 5; i++) {
        System.out.print("请按任意键完成抽奖");
        String key = sc.nextLine();
        int index = r.nextInt(arr.length);
        int number = arr[index];
        System.out.println("恭喜您,抽中了" + number);
        if (i == 4) {
            System.out.println("活动结束...");
            break;
        }
        arr = getArrayByIndex(arr, index);
    }
}

public static int[] getArrayByIndex(int[] arr, int index) {
    int[] result = new int[arr.length - 1];
    for (int i = 0; i < result.length; i++) {
        if (i < index) {
            result[i] = arr[i];
        } else {
            result[i] = arr[i + 1];
        }
    }
    return result;
}