杨辉三角，手动输入行数---Java

package practice.people.apple;
import java.util.Scanner;

public class YangHui {
public static void main(String[] args) {
	Scanner myscanner = new Scanner(System.in);
	System.out.println("请输入杨辉三角层数");
	int nums = myscanner.nextInt();
	//为nums开辟空间
	int[][] arr = new int[nums][];
	
	//外层循环
	for(int i = 0;i < arr.length; i++) {
	//为每层循环开辟空间
		arr[i]=new int[i+1];
	
	//为第一个数和最后一个赋值为1
		for(int j = 0;j < arr[i].length; j++) {
			if(j == 0 || j == arr[i].length-1) {
				arr[i][j] = 1;
			}
			else {
					arr[i][j] = arr[i-1][j]+arr[i-1][j-1];
			}
		}

	}
	//利用循环输出数组
	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();
	}
}
}