Java之杨辉三角的实现

今天突然想温习一下Java的基础，想了想就写写杨辉三角吧

1、直接法，利用二维数组

 1 import java.util.Scanner;
 2 public class Second
 3 {
 4     public static void main(String[] args) {
 5         // TODO Auto-generated method stub
 6         Scanner in=new Scanner(System.in);
 7         int n=in.nextInt();
 8         int[][] Arr = new int[n][];
 9         in.close();
10         for(int i = 0; i < Arr.length; i++)
11         {
12             Arr[i] = new int[i + 1];
13             Arr[i][0] = 1;
14             Arr[i][i] = 1;
15             for(int j = 0; j < Arr[i].length - 1; j++)
16                 if(j >= 1 && i > 1)
17                     Arr[i][j] = Arr[i - 1][j - 1] + Arr[i - 1][j];
18         }
19         for(int i = 0; i < Arr.length; i++)
20         {
21             for(int j = 0; j < Arr.length - Arr[i].length; j++)
22                 System.out.print(" ");
23             for(int j = 0; j < Arr[i].length; j++)
24             {
25                 System.out.print(Arr[i][j]);
26                 System.out.print(" ");
27             }
28             System.out.println();
29         }
30     }
31 }

2、使用递归方式

 1 public class Second
 2 {
 3     public static int assign(int x,int y)
 4     {
 5         int z;  
 6         if(y==1||y==x)
 7             return 1; 
 8         z=assign(x-1,y-1)+assign(x-1,y);  
 9         return z;
10     }
11     public static void main(String args[])
12     {
13         for (int i=1; i<=5; i++) 
14         {
15             for (int j=1; j<5-i+1; j++)
16                 System.out.print(" ");//打印空格  
17             for(int j=1;j<=i;j++)
18                 System.out.print(assign(i,j)+" ");
19         System.out.println();
20         }
21     }
22 }