not an issue.

Array basically looks like this, right?

[1, 2, 3, 4, 5 ]
[6, 7, 8, 9, 10]
[11, 12, 13, 14, 15]
[16, 17, 18, 19, 20]
[21, 22, 23, 24, 25]

So you're going:

right --->
^down
|**|
|********v
up<-----left

So you do start at

--------->
1,2,3,4,5|
********6|
********7|
********8|
********9V
********10

Etc.

Did my best with formatting lol.

Ps., in your example, you have 6 in your first array (1-10) and 4 in your second (6-9). 10 belongs at the end of the second array.

The 2nd hidden test case is "abcdefghba".
There exists no substring within the string that is a palindrome.
Therefore the length of the longest substring is any of the letters.
So the answer is 1. I hope this helps.

@kgashok, can you please explain the 2nd hidden test case? I don't see a palindrome :(