Java，数字金字塔

Question

I know there is a lot of threads about this easy task, but I still need to put an extra for loop somewhere.

Thus far, I managed to do this:

public static void trikotnik(int n){
    for (int i = 1; i <= n; i++ )
       {
          for (int j = 1; j < n; j++ )
            System.out.print(" ");

          n--;

          for (int k = 1; k <= 2*i - 1; k++ )
              System.out.print(k);

          System.out.println("");
       }
}

which outputs a nice pyramide (ignore format, i dunno how to do it properly).
1
1 2 3
1 2 3 4 5
1 2 3 4 5 6 7
1 2 3 4 5 6 7 8 9

However, my pyramide needs to look like this:
1
2 3 4
3 4 5 6 7
4 5 6 7 8 9 0
5 6 7 8 9 0 1 2 3

Thank you for your help and suggestions!

Answer 1

just change the value of k in your second loop like below (start with i and border 3*i-2 ):

for (int i = 1; i <= n; i++ )
   {
      for (int j = 1; j < n; j++ )
        System.out.print(" ");

      n--;

      for (int k = i; k <=3*i-2; k++ )
          System.out.print(k%10);

      System.out.println("");
   }

OUTPUT:

        1
       234
      34567
     4567890
    567890123
   67890123456
  7890123456789
 890123456789012
.................

Answer 2

The Simple Solution: use a counter outside of the loop and ignore the inside process. Add one to it on each call and take that value modulo 10.

public static void trikotnik(int n) {
    int val = 1;
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j < n; j++)
            System.out.print(" ");

        n--;

        for (int k = 1; k <= 2 * i - 1; k++)
            System.out.print(val++%10);

        System.out.println("");
    }
}

Output:

    1
   234
  56789
 0123456
789012345