Solved

squareUp  challenge

Posted on 2016-08-14
22
186 Views
Last Modified: 2016-08-23
Hi,

I am working on below challenge
http://codingbat.com/prob/p155405

Array-3 > squareUp
prev  |  next  |  chance
Given n>=0, create an array length n*n with the following pattern, shown here for n=3 : {0, 0, 1,    0, 2, 1,    3, 2, 1} (spaces added to show the 3 groups).

squareUp(3) → [0, 0, 1, 0, 2, 1, 3, 2, 1]
squareUp(2) → [0, 1, 2, 1]
squareUp(4) → [0, 0, 0, 1, 0, 0, 2, 1, 0, 3, 2, 1, 4, 3, 2, 1]
0
Comment
Question by:gudii9
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 8
  • 6
  • 5
  • +1
22 Comments
 
LVL 7

Author Comment

by:gudii9
ID: 41756424
Given n>=0, create an array length n*n with the following pattern, shown here for n=3 : {0, 0, 1,    0, 2, 1,    3, 2, 1} (spaces added to show the 3 groups).

squareUp(3) → [0, 0, 1, 0, 2, 1, 3, 2, 1]
squareUp(2) → [0, 1, 2, 1]
squareUp(4) → [0, 0, 0, 1, 0, 0, 2, 1, 0, 3, 2, 1, 4, 3, 2, 1]

i have not understood the challenge description.

How below are expected outputs?

squareUp(3) → [0, 0, 1, 0, 2, 1, 3, 2, 1]
squareUp(2) → [0, 1, 2, 1]
squareUp(4) → [0, 0, 0, 1, 0, 0, 2, 1, 0, 3, 2, 1, 4, 3, 2, 1]
0
 
LVL 38

Accepted Solution

by:
Gerwin Jansen, EE MVE earned 250 total points
ID: 41756439
You shift the numbers into the array from the right in groups. Example for 5:

0,0,0,0,1
0,0,0,2,1
0,0,3,2,1
0,4,3,2,1
5,4,3,2,1
0
 
LVL 27

Expert Comment

by:d-glitch
ID: 41756501
As a warm-up, how would you make an array that contained the integers from  0  to  n² -1 ??
0
PeopleSoft Has Never Been Easier

PeopleSoft Adoption Made Smooth & Simple!

On-The-Job Training Is made Intuitive & Easy With WalkMe's On-Screen Guidance Tool.  Claim Your Free WalkMe Account Now

 
LVL 7

Author Comment

by:gudii9
ID: 41756527
You shift the numbers into the array from the right in groups. Example for 5:

0,0,0,0,1
0,0,0,2,1
0,0,3,2,1
0,4,3,2,1
5,4,3,2,1
this is clear now. let me think on it now
0
 
LVL 38

Expert Comment

by:Gerwin Jansen, EE MVE
ID: 41756564
OK ;)
0
 
LVL 7

Author Comment

by:gudii9
ID: 41760204
looks like i may need two loops for this also
0
 
LVL 7

Author Comment

by:gudii9
ID: 41760209
You shift the numbers into the array from the right in groups. Example for 5:
how to represent this push in code?
0
 
LVL 27

Assisted Solution

by:d-glitch
d-glitch earned 125 total points
ID: 41760380
You shift the numbers into the array from the right in groups. Example for 5:
0,0,0,0,1
0,0,0,2,1
0,0,3,2,1
0,4,3,2,1
5,4,3,2,1

You don't have to build the array by shifting.

What numbers are in the first row?
And the second?
Do you see the pattern?
And the pattern in the number of 0's?
0
 
LVL 7

Author Comment

by:gudii9
ID: 41764758
not yet
0
 
LVL 35

Assisted Solution

by:mccarl
mccarl earned 125 total points
ID: 41764796
not yet

Wow, how about now with some extra spaces in certain spots...

0,0,0,0,     1
0,0,0,     2,1
0,0,     3,2,1
0,     4,3,2,1
     5,4,3,2,1
0
 
LVL 27

Expert Comment

by:d-glitch
ID: 41765353
"Wow" indeed.
Do you realize that printing the array in an n x n grid rather than an n² x 1 string is an enormous hint?
0
 
LVL 7

Author Comment

by:gudii9
ID: 41765452
Do you realize that printing the array in an n x n grid rather than an n² x 1 is an enormous hint?
not able to realize. I just see some additional spaces.


0,0,0,0,1
0,0,0,2,1
0,0,3,2,1
0,4,3,2,1
5,4,3,2,1

compared to above below?

0,0,0,0,     1
0,0,0,     2,1
0,0,     3,2,1
0,     4,3,2,1
     5,4,3,2,1
0
 
LVL 27

Expert Comment

by:d-glitch
ID: 41765550
There are two ways to build an array with n² elements:

  for i= 0 to n² by 1

  for i= 0 to n by 1
     for j= 0 to n by 1

The second method might be useful if you can see the pattern in the grid.
0
 
LVL 7

Author Comment

by:gudii9
ID: 41767259
 for i= 0 to n by 1
     for j= 0 to n by 1

The second method might be useful if you can see the pattern in the grid.

which grid? what is grid?
you mean below?
0,0,0,0,     1
0,0,0,     2,1
0,0,     3,2,1
0,     4,3,2,1
     5,4,3,2,1

to me above looks lik e2 D array not 1 Dimensional?
0
 
LVL 27

Expert Comment

by:d-glitch
ID: 41767319
Yes, you have to build a 1-D array.
Gerwin Jansen gave you an enormous hint by drawing it as an nxn matrix so you can see the pattern.
1
 
LVL 38

Expert Comment

by:Gerwin Jansen, EE MVE
ID: 41767330
The grid is the 2D array we've shown you to help understand the question. Your function should return a single string of numbers.

squareUp(2) → [0, 1, 2, 1]
0,1
2,1

squareUp(1) → [0, 1]
0
1
0
 
LVL 27

Expert Comment

by:d-glitch
ID: 41767502
I am sure this is not correct.  There can only be n*n elements.
squareUp(1) → [0, 1]

0
1

The answer is probably [1], but it may depend on your implementation.

And squareUp(0) → [ ]  because it must have 0*0 elements.
0
 
LVL 38

Expert Comment

by:Gerwin Jansen, EE MVE
ID: 41767626
@d-glitch - You are correct, 1*1=1 :D

squareUp(1) would have to result in [1] - independent of the implementation.

Each group is n wide starting with a 1 on the right side, this would result in [1]
0
 
LVL 7

Author Comment

by:gudii9
ID: 41767634
public int[] squareUp(int n) {
  
	    int[] finalRes = new int[n * n];
	    int indx = 0;
	 
	    for (int i = 1; i <= n; i++) {
	        for (int k = 1; k <= n - i; k++)
	        	finalRes[indx++] = 0;
	        for (int j = i; j > 0; j--) 
	        	finalRes[indx++] = j;
	    }
	    return finalRes;
	
}

Open in new window


above passes all tests.
Expected      Run            
squareUp(3) → [0, 0, 1, 0, 2, 1, 3, 2, 1]      [0, 0, 1, 0, 2, 1, 3, 2, 1]      OK      
squareUp(2) → [0, 1, 2, 1]      [0, 1, 2, 1]      OK      
squareUp(4) → [0, 0, 0, 1, 0, 0, 2, 1, 0, 3, 2, 1, 4, 3, 2, 1]      [0, 0, 0, 1, 0, 0, 2, 1, 0, 3, 2, 1, 4, 3, 2, 1]      OK      
squareUp(1) → [1]      [1]      OK      
squareUp(0) → []      []      OK      
squareUp(6) → [0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 2, 1, 0, 0, 0, 3, 2, 1, 0, 0, 4, 3, 2, 1, 0, 5, 4, 3, 2, 1, 6, 5, 4, 3, 2, 1]      [0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 2, 1, 0, 0, 0, 3, 2, 1, 0, 0, 4, 3, 2, 1, 0, 5, 4, 3, 2, 1, 6, 5, 4, 3, 2, 1]      OK      

All Correct

any improvements/refinements/alternate approaches?
0
 
LVL 38

Expert Comment

by:Gerwin Jansen, EE MVE
ID: 41767645
It is passing all tests, code looks OK to me.
0

Featured Post

Free Tool: Subnet Calculator

The subnet calculator helps you design networks by taking an IP address and network mask and returning information such as network, broadcast address, and host range.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
ejb stateless example 2 68
ejb entity bean example 2 57
ejb mdb examples 1 39
What is the use of Forwarding Class in java 1 53
In this post we will learn different types of Android Layout and some basics of an Android App.
International Data Corporation (IDC) prognosticates that before the current the year gets over disbursing on IT framework products to be sent in cloud environs will be $37.1B.
The viewer will learn how to user default arguments when defining functions. This method of defining functions will be contrasted with the non-default-argument of defining functions.
In this fourth video of the Xpdf series, we discuss and demonstrate the PDFinfo utility, which retrieves the contents of a PDF's Info Dictionary, as well as some other information, including the page count. We show how to isolate the page count in a…

734 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question