2009-04-13技术学习：Java 杨辉三角

 

算法不熟就是不行啊，一个杨辉三角都写了半个小时才搞定:(

在CoreJava第三章中有讲到多维数组，这让我想到了杨辉三角，就试着写一下Java的实现：

public static void main(String[] args) { Scanner in = new Scanner(System.in); System.out.println("Input a number:"); int number = in.nextInt(); int[][] arr = new int[number][number]; for (int i = 0; i < number; i++) { for (int j = 0; j <= i; j++) { if (j == 0 || i == j) { arr[i][j] = 1; } else { arr[i][j] = arr[i - 1][j - 1] + arr[i - 1][j]; } System.out.print(arr[i][j] + " "); } System.out.println(""); } } 

 

修改了一下OO思想实现：

YHTriangle.java:

public class YHTriangle { private int number; private int[][] array; public YHTriangle(int num) { setNumber(num); int columns = getNumber(); array = new int[columns][columns]; for (int i = 0; i < getNumber(); i++) { for (int j = 0; j <= i; j++) { if (j == 0 || i == j) { array[i][j] = 1; } else { array[i][j] = array[i - 1][j - 1] + array[i - 1][j]; } } } } public void printTriangle() { for (int i = 0; i < getNumber(); i++) { for (int j = 0; j < i; j++) { System.out.print(array[i][j] + " "); } System.out.println(""); } } public int getNumber() { return number; } public void setNumber(int number) { this.number = number; }} 

测试java:

import java.util.*;public class TestYH { public static void main(String[] args) { Scanner in = new Scanner(System.in); System.out.println("Input a number:"); int number = in.nextInt(); YHTriangle yh = new YHTriangle(number); yh.printTriangle(); }} 

新手啊，要不停的练习练习！