杨晖三角形如果要居中输出的话，怎么办？

   求大家帮忙
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不居中输出的代码如下：import java.io.*;
public class YangHui
{public static void main(String args[])throws IOException
{
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
String str=br.readLine();
int ROW=Integer.parseInt(str);
int a[][]=new int[ROW+1][];
for(int i=0;i<=ROW;i++)
{
a[i]=new int[i+1]; //指定每行的列数

}
yanghui(a,ROW);
}

static void yanghui(int a[][],int ROW)
{

for(int i=0;i<=ROW;i++)
for(int j=0;j<=a[i].length-1;j++)
{
if(i==0||j==0||j==a[i].length-1)
a[i][j]=1;
else a[i][j]=a[i-1][j-1]+a[i-1][j];

}
for(int i=0;i<=ROW;i++)
{
for(int j=0;j<=a[i].length-1;j++)
System.out.print(a[i][j]+" ");
System.out.println();
}

}
}

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怎么没人回答呀

急！！！
----------------解决方案--------------------------------------------------------

我也刚学JAVA，你看看这样编可以吧，呵呵，方法比较笨
import java.io.*;
public class YangHui
{public static void main(String args[])throws IOException
{
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
String str=br.readLine();
int ROW=Integer.parseInt(str);
int a[][]=new int[ROW+1][];
for(int i=0;i<=ROW;i++)
{
a[i]=new int[i+1];

}
yanghui(a,ROW);
}

static void yanghui(int a[][],int ROW)
{

for(int i=0;i<=ROW;i++)
for(int j=0;j<=a[i].length-1;j++)
{
if(i==0||j==0||j==a[i].length-1)
a[i][j]=1;
else a[i][j]=a[i-1][j-1]+a[i-1][j];

}
for(int i=0;i<ROW;i++)
{
int e=1;
while(e<ROW-i){
System.out.print(" ");
e++;
}
for(int j=0;j<=a[i].length-1;j++)
System.out.print(a[i][j]+" ");
System.out.println();
}

}
}

----------------解决方案--------------------------------------------------------