Creating number pattern with minimum for loops

Question

How to create the following number pattern with minimum for loops. Is there any names given mathematically for the pattern of numbers as like Fibonacci, pascal's triangle, any-other interesting patterns which are complicated but possible using for-loops ?

Expected O/P Pattern:

// For loops only prints only from 1 to 5 it prints correctly and on reversing there comes the wrong output.

for(int i=1; i<10; i++)
{
for(int j=1,k=10; j<=i&&k>5; j++,k--)   
        {
            if(i<=5)
            System.out.print(i);
            else
            if(i>5)
            System.out.print(i);
        }
            System.out.println();
}

@RandMate you should check my solution, it is generic and simpler to read. — Juvanis, Oct 07 '12 at 18:50

score 2 · Accepted Answer · edited Oct 07 '12 at 18:47

2

here you are:

for (int i = 1, j = 1 ; i < 10 ; i++, j = (i <= 5) ? (j*10 + 1) : (j/10))
    System.out.println(i * j);

edited Oct 07 '12 at 18:47

arshajii

127,459
24
238
287

answered Oct 07 '12 at 18:30

Serge

6,088
17
27

@RandMate i expect you try my solution. – Juvanis Oct 07 '12 at 19:16

score 2 · Answer 2 · answered Oct 07 '12 at 18:50

2

Another solution with a simpler logic:

public static void main(String[] args) {
    int input = 5;

    for (int i = 1; i <= 2 * input - 1; i++) {
        for (int j = 0; j < input - Math.abs((input - i)); j++)
            System.out.print(i);
        System.out.println();
    }
}

You print the elements with respect to the absolute value of their difference from input. If you change the input to another value this will still work.

answered Oct 07 '12 at 18:50

Juvanis

25,802
5
69
87

1

the iteration is understandable than the previous one, which model of code is efficient by the way, – Rand Mate Oct 08 '12 at 09:34
1

Sergei's answer uses 1 loop, but mine uses 2 loops. So for bigger numbers of input (in our case it's 5) his code will run faster, I guess. anyway, you can upvote my answer if it is smart. – Juvanis Oct 08 '12 at 09:57

score 1 · Answer 3 · answered Oct 07 '12 at 19:36

Here's a solution with no loops (recursive)

public class NumberTriangle {        

    public static void print(int top_, int count_, int length_) {
        int top = top_;
        int count = count_;
        int length = length_;
        count++;        

        if (count <= top){
            length++;           
        } else {
            length--;
        }

        if (length == 0) {
            return;
        }       

        String s = String.format(String.format("%%0%dd", length), 0).replace("0",""+count);     
        System.out.println(s);

        NumberTriangle.print(top, count, length);
    }

    public static void main (String args[]){

        NumberTriangle.print(5,0,0);

    }   

}

score 0 · Answer 4 · answered May 05 '16 at 07:11

java-8 solution for the problem:

IntStream.range(MAX * -1, MAX)
            .forEach(i -> IntStream.rangeClosed(1, MAX - Math.abs(i))
                    .mapToObj(j -> j == MAX - Math.abs(i) ? MAX - Math.abs(i) + "\n" : MAX - Math.abs(i) + " ")
                    .forEach(System.out::print)
            );

user1936887 · Answer 5 · 2012-12-30T04:13:03.600

@RandMate you could do it this way: to print this pattern you will have to divide the pattern into 2 parts and use two sets of nested for loop: here goes: int i,j,p; /first nested loop to print 1 22 333 4444 55555/ for(i=1;i<=5;i++)
{ for(j=1;j<=i;j++) { System.out.print(i); } System.out.println(); }

/*this is the second nested loop to print
 6666
 777
 88
 9 */
    p=6;
  for(i=4;i>=1;i--)
  {
   for(j=1;j<=i;j++)
   {
    System.out.print(p);
   }
    p=p+1;
   System.out.println();
  }

  Hope it was helpul.
  ALL THE BEST......enjoy!

Creating number pattern with minimum for loops

5 Answers5