Displaying output for the given format

[Subhash Pavuskar]

Program to Display as below(input is 4) - turned out not to be so simple!
1
1 2 2 1
1 3 3 3 1
1 4 4 4 4 1
1 5 5 5 5 5 1

Can Anyone Explain me the logic ?

[Pranav Raulkar]

I seem to get it a bit. Lets try,

When i = 1, print 1 only once - 1
when i = 2, print 2, twice, but enclosed between 1 at the starting and ending - 1221
when i = 3, print 3, thrice, but enclosed between 1 at the starting and ending - 13331
when i = 4, print 4, 4 times, but enclosed between 1 at the starting and ending - 144441
when i = 5, print 5, 5 times, but enclosed between 1 at the starting and ending - 1555551

What I'm not getting is the relation of input value 4 with the output. I mean if the loop starts at 1 and is <=4 only this should get printed
1
1 2 2 1
1 3 3 3 1
1 4 4 4 4 1

Are you sure the input is 4? and not 5?

[Subhash Pavuskar]

Assume that Input is :5

and show me the programming logic........

Actually i have program but i am not getting still logic behind it .

public class DesignPattern
{

	
	public static void main(String[] args)
	{
		Scanner sc = new Scanner(System.in);
		System.out.println("Enter input number");
		int num;
		while(!sc.hasNextInt())
		{
			System.out.println("Enter proper int number as input...");
			sc.nextLine();
		}
		num = sc.nextInt();		
		for (int i=1; i <= num; i++)
		{
			for(int k=1;k<=(num-i);k++)
				System.out.print(" ");
			
			if(i!=1)
				System.out.print("1 ");
			else
				System.out.print("  ");
			for (int j=1; j<=i;j++)
				System.out.print(i+" ");
			if(i!=1)
				System.out.print("1");
			System.out.println("");
		}
		
	}

}

if you understood then comment on each single line.

[Pranav Raulkar]

First of all, use code tags while posting code. The code you posted is very hard to read as its not even formatted.

Secondly, I cant get how are you not getting the logic? Your wrote this code (hopefully), and it runs absolutely fine

Finally my logic for this, a bit simpler

System.out.println("Enter input number: ");

Scanner sc = new Scanner(System.in);
int num = sc.nextInt();

for (int i = 1; i <= num; i++) {
	if (i != 1) System.out.print(1);
	for (int j = 1; j <= i; j++) System.out.print(i);
	if (i != 1) System.out.println(1);
	else System.out.println();
}

[Subhash Pavuskar]

That program is not written by me :P

[John Jai]

So you want to understand a program that's already written... When I ran your program, it was having some additional spaces in the output like below

Enter input number
5
      1
    1 2 2 1
   1 3 3 3 1
 1 4 4 4 4 1
1 5 5 5 5 5 1

So you have to add starting and ending white spaces in Pranav's solution.

The code you posted with some clarification comments below... And use opening and closing braces for loops and conditions. It would be helpful for you to understand the program easily.

package ranch;

import java.util.Scanner;

public class DesignPattern {

	public static void main(String[] args) 
	{ 
		Scanner sc = new Scanner(System.in); 
		System.out.println("Enter input number"); 
		int num; 
		while(!sc.hasNextInt()) 
		{ 
			System.out.println("Enter proper int number as input..."); 
			sc.nextLine(); 
		} 
		// Below line reads the input from the user. Say if user enters 5, it gets saved to the num variable
		num = sc.nextInt();	

		// Below for loop loops from 1 to the user given input (say 5). For the rest think user has input 5.
		// so it reads for (int i = 1; i < = 5; i++) - means its going to iterate 5 times.
		for (int i=1; i <= num; i++) 
		{ 
			
			// Below for loop is used to print the spaces at the beginning of each line
			// so you have for the first iteration (when i = 1) -> for (k = 1; k <= 4; k++) 
			// similarly for the second iteration (when i = 2) -> for (k = 2; k <= 3; k++)
			for(int k=1;k<=(num-i);k++) {
				System.out.print(" "); 
			}

			// This prints the value 1 at the start. Note that when i = 1, the beginning "1" is not printed 
			if(i!=1) {
				System.out.print("1 ");
			}
			else {
				// i is not equal to 1 ... so don't print i... print only the space..
				System.out.print(" ");
			}
			
			// Below is the main for loop that prints the actual value (1, 2 , 3 , 4)
			for (int j=1; j<=i;j++) {
				// Print 1 one time, 2 two times, 3 three times.. and so on... 
				// It prints a space after printing the number...
				System.out.print(i+" ");
			}
			
			if(i!=1) {
				// This prints a "1" at the end of the line when i is not equals to 1..
				// i.e prints "1" at end of every line starting from the second one...
				System.out.print("1");
			}
			
			// Below println() method makes a new line at the end... so that the other print() methods following it prints on the next line
			System.out.println("");		
			
		} 

	} 

} 

[fred rosenberger]

Subhash Pavuskar,

I added code tags to your post to make it more legible. next time highlight your code then hit the 'code' button above, just like you wanted to make it bold or italic.