杨辉三角

package array.test;

public class Test2 {
    public static void main(String[] args) {
        //1. 声明并初始化二维数组
        int[][] arr = new int[10][];

        //2.给数组元素赋值
        for (int i = 0;i < arr.length;i++){
            arr[i] = new int[i+1];

            //2.1给首末元素赋值
            arr[i][0] = arr[i][i] = 1;

            //2.2给每行的非首末元素赋值
            if(i > 1){
                for(int j  = 1;j < arr[i].length-1;j++){
                    arr[i][j] = arr[i-1][j-1] + arr[i-1][j];
                }
            }
        }

        //3.遍历二维数组
        for (int i = 0;i < arr.length;i++){
            for (int j = 0;j < arr[i].length;j++){
                System.out.print(arr[i][j] + " ");
            }
            System.out.println();
        }
    }
}