Problem 11. Back and Forth Rows

Created by Cody Team

Solve Later

Given a number n, create an n-by-n matrix in which the integers from 1 to n^2 wind back and forth along the rows as shown in the examples below.

Examples:

 Input  n = 3
 Output a = [ 1 2 3
              6 5 4
              7 8 9 ]

 Input  n = 4
 Output a = [ 1     2     3     4
              8     7     6     5
              9    10    11    12
             16    15    14    13 ]

Solve

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17299 Solutions
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Last Solution submitted on Nov 22, 2024

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16 Comments

16 Comments

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Mandeep Singh on 14 Jun 2013

nice one

André on 24 Jun 2014

good one

ABDELRAHMAN on 12 Dec 2015

i got same solution on matlab, but i don't know why i didn't here

Samarth Shivaswamy on 28 Dec 2015

I am no expert, but does anyone else think that the first test case is flawed? "%%n = 4;" instead of " %% (new line) n = 4;" So, "n" is never defined for the first case. Am I right? If not, I apologize!

shahin rmz on 29 Oct 2016

that seems legit

Aniket Patil on 7 Mar 2017

nice one

UnCroissant on 7 May 2017

Really enjoyed this one.

Loris Chavée on 17 Jul 2017

Can someone help me? My solution works on my matlab but gives me an error during the test! What am I supposed to do ? :(

Kyle Chappell on 8 Nov 2017

I think the answer to test suite 5 should be c = 2 since the first row is 0.21 and the second is 0.26. Please correct me if I'm wrong.

Lányi György on 13 Mar 2018

Awesome!

christopher Minix on 24 Apr 2018

Awesome

Majid Farzaneh on 17 May 2018

Great

Shizun Li on 31 Oct 2018

Check this out.
function b = back_and_forth(n)
b=1:n^2;
b=reshape(b,n,n)';
for i=2:2:n
b(i,:)=fliplr(b(i,:));
end
end

Sharon Spelt on 8 Nov 2018

It appears a '\r' is needed after the %% in the first test of the solution to make it process properly.

goc3 on 9 Nov 2018

The problem with the first test case has been fixed here.

Aleksandrov Igor on 14 Jan 2020

This code
b=vec2mat(1:n^2,n)
b(2:2:end,:)=fliplr(b(2:2:end,:))
work in Matlab, why it doesn't works on site?

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Problem 11. Back and Forth Rows

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Problem 11. Back and Forth Rows

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