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recursive function to check a Palindrome

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Urmish Haribhakti
Urmish Haribhakti on 10 Sep 2020
Commented: Harsh Mittal on 20 Oct 2020
function out=palindrome(x)
n=numel(x);
if n==1
out=true;
else
Can anyone continue from here?

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Answers (3)

John D'Errico
John D'Errico on 11 Sep 2020
Why not try? I won't write it for you, as the entire problem is to make you think. I'll give you one hint, and I will hope nobody does the rest of your homework for you.
A vector is a palindrome if the first and last elements are the same, AND...
.... what else? That is, what information do you need about the rest of the vector? Is there some way you can treat this in a recursive way?
This is your homework, not ours, remember.

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Harsh Mittal
Harsh Mittal on 20 Oct 2020
I tried writing the code but i am getting error as "MATLAB:TooManyOutputs" , can anyone help me resolve this error, i recieved this error while submiting my code

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Johannes Hougaard
Johannes Hougaard on 10 Sep 2020
There is no need to make it recursive or to look for multiple numel's
function out = palindrom(x)
x = upper(char(varargin{1})); % to account for inputs being UPPER/lower case and/or a string rather than a char
n = length(x);
iseven = rem(n,2) == 0;
middle = ceil(n/2);
if ~iseven
out = all(x(1:middle) == fliplr(x(middle:end)));
else
out = all(x(1:middle) == fliplr(x(middle+1:end)));
end
end

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Johannes Hougaard
Johannes Hougaard on 11 Sep 2020
Valid point - classic example of overthinking a simple problem :S
Urmish Haribhakti
Urmish Haribhakti on 11 Sep 2020
Correct. Obviously, very simple to do it normally. Any idea on how to make it recursive?
Selvakumar T
Selvakumar T on 25 Sep 2020
function Result = palindrome(t) if length(t) <= 1 Result= true; else Result= (t(1) == t(end) &&palindrome(txt(2:end-1))); end end

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Wai Han
Wai Han on 18 Oct 2020
Edited: Wai Han on 18 Oct 2020
Hello Urmish Haribhakti,
I suggest you to try your best like John D'Errico said.
But somehow, I can help you out by telling you the concept, (maybe a pseudocode).
% The input is a string which is in term a char array.
% Firstly, if the length of the string is 1, or isempty!! then the function should return logical 1 (true).
% elseif length ~= 1,check the first and last value of the vector,
% if first == last
% recall the function by removing those two values. for example, vector(2:end-1)
% Lastly, if the first and last value are not equal, the your output should be logical 0 (false).
I hope this can help you out!

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