Java二维数组打印杨辉三角形

    public static void main(String[] args) {        Scanner sc = new Scanner(System.in);        System.out.println("请输入一共多少行");        int n = sc.nextInt();        int[][] arr = new int[n][n];        for (int i = 0; i < arr.length; i++) {            for (int j = 0; j < arr[i].length; j++) {                arr[i][0] = 1;                arr[i][i] = 1;            }        }        for (int i = 2; i < arr.length; i++) {            for (int j = 1; j < arr[i].length - 1; j++) {                arr[i][j] = arr[i - 1][j - 1] + arr[i - 1][j];            }        }        for (int i = 0; i < arr.length; i++) {            for (int j = 0; j <= i; j++) {                System.out.print(arr[i][j] + "\t");            }            System.out.println();        }    }/*思路：第一列和最后一列都是1；     从第三行开始每一列等于上一行那列和前列相加。     输出结果：1   1   1   1   2   1   1   3   3   1   1   4   6   4   1   1   5   10  10  5   1   1   6   15  20  15  6   1   1   7   21  35  35  21  7   1   1   8   28  56  70  56  28  8   1   1   9   36  84  126 126 84  36  9   1   */