基础训练2-杨辉三角_任务描述 本关任务:用倒推法求杨辉三角并输出。 编程要求 请在右侧编辑器begin-en

import java.util.Arrays;
import java.util.Scanner;
 
public class Main {
	public static void main(String args[]) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int[][] arr = new int[n][n];
		for (int i = 0; i < n; i++)
			Arrays.fill(arr[i], 1);
		for (int i = 1; i < n; i++) {
			for (int j = 1; j < i; j++) {
				arr[i][j] = arr[i - 1][j - 1] + arr[i - 1][j];
			}
		}
		for (int i = 0; i < n; i++) {
			for (int j = 0; j <= i; j++) {
				System.out.print(arr[i][j] + " ");
			}
			System.out.println();
		}
	}
}

import java.util.Scanner;
 
public class Main {
	public static void main(String args[]) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		// n为行，r为列
		for (int n = 0; n < N; n++) {
			for (int r = 0; r <= n; r++) {
				int i = 1;
				long s = 1;
				while (i <= r) {
					// 第n行的第m个数和第n-m+1个数相等，
					// 即C(n-1,m-1)=C(n-1,n-m)，这是组合数性质
					// 组合数计算方法：C(n,m)=n!/[m!(n-m)!]
					s = s * (n - i + 1) / i;
					i++;
				}
				System.out.print(s + " ");
			}
			System.out.println();
		}
	}
}