Java：利用二维数组构建杨辉三角(帕斯卡三角)

package com.zbj.demo;

import java.util.Scanner;

import org.junit.Before;
import org.junit.Test;

public class PascalTriangle {
	int n = 0;

	@Before
	public void scan() {
		Scanner scan = new Scanner(System.in);
		System.out.println("请输入杨辉三角的行数：");

		while (n <= 2) { // 控制正确行数
			n = scan.nextInt();
			if (n <= 2) {
				System.out.println("杨辉三角必须大于2行,请重新输入");
			}
		}
	}

	@Test
	public void pascaltriangle() {
		int[][] arr = new int[n][n];
		// 每行的首尾都为1
		for (int i = 0; i < arr.length; i++) {
			arr[i][0] = 1;
			arr[i][i] = 1;
		}

		// 每行的第二列起都是上一行的同一列+上一行的前一列
		for (int i = 2; i < arr.length; 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 < arr.length; i++) { // 遍历杨辉三角
			for (int j = 0; j <= i; j++) { // 后面无用部分无需遍历
				System.out.print(arr[i][j] + " ");
			}
			System.out.println();
		}
	}
}

标签：Java,Scanner,scan,System,帕斯卡,杨辉三角,import,public
来源： https://blog.csdn.net/weixin_43810579/article/details/89880917