1 2 1

输出：
   1
  121
12321
1234321

class PrintOneRow {
private int length;
public PrintOneRow(int length) {
  this.length = length;
}
public void printRow() {
  for (int i = 0; i <= length/2; i++) {
   System.out.print(i+1);
  }
  for (int j = 0; j < length/2; j++) {
   System.out.print(length / 2 - j);
  }
  System.out.println();
}
}
class PrintNum {
public static void main(String[] args) {
  int numOfRows = 4;
  PrintOneRow printOneRow;
  for (int i = 1; i <= numOfRows; i++) {
   for (int j = 0; j < numOfRows - i; j++) {
    System.out.print(" ");
   }
   new PrintOneRow(2 * i - 1).printRow();
  }
}
}