从用户获取输入并打印数字的递减模式

Question

Can someone help me write a code that prints the following pattern.

987654321
 98765432
  9876543
   987654
    98765
     9876
      987
       98
        9          

This is my code sample but I am getting the exact opposite of the above pattern.

        height = getInPut("Enter the height of the triangle");
        int h = Integer.parseInt(height);
        int start = h, num=1,max=h;

        for (int r= 1; r <=h; r++)
        {
            System.out.println();
            for (int j = 1; j<= max; j++)
            {
                if(h>=6 && h<=10) 
                {
                    System.out.print(num);  
               }else{
                   System.out.println("height should be between 6-10");
                   System.exit(0);
               }

              num++;
            }
           num= r+1;
           max--;
            }

Thanks in advance!!

Answer 1

I would start with an initial value of 987654321 in a StringBuilder , then loop while that contains characters; in every iteration of the loop, we want to print the difference (in spaces) between the initial length (nine) and the current length of the StringBuilder , then print the contents of the StringBuilder before removing the last character. Like,

StringBuilder sb = new StringBuilder("987654321");
while (sb.length() > 0) {
    for (int i = 0; i < 9 - sb.length(); i++) {
        System.out.print(' ');
    }
    System.out.println(sb);
    sb.setLength(sb.length() - 1);
}

Which outputs (as requested)

987654321
 98765432
  9876543
   987654
    98765
     9876
      987
       98
        9

I'll leave filling the initial StringBuilder and adjusting nine into a variable as an exercise for the reader.