Golf Recamán's sequence

9 views (last 30 days)
John Doe
John Doe on 23 Sep 2014
Recamán's sequence described in pseudo-code is as follows:
A(0) = 0
A(n) = A(n-1) - n if A(n-1) - n > 0 and is new, else
A(n) = A(n-1) + n
The 11 first elements is:
0, 1, 3, 6, 2, 7, 13, 20, 12, 21, 11
As a challenge, I should write a function that outputs the first n elements, in as few characters as possible, where the number of elements to display should be used as input to the function. The best I can do is 90 characters:
function A=f(n)
A=0;for i=1:n-1 b=A(i)-i;A(i+1)=b+2*i;if b>0&&~any(A==b) A(i+1)=b;end;end
(written out):
function A = Recamans(n)
A = zeros(1,n);
A(1) = 0;
for ii = 1:n-1
b = A(ii)-ii;
A(ii+1) = b + 2*ii;
if b > 0 && ~any(A == b)
A(ii + 1) = b;
end
end
end
MY question is: Is it possible to do this in fewer characters in MATLAB?

Answers (1)

George Iskander
George Iskander on 5 Feb 2020
function x=Recaman_seq(n)
x=zeros(1,n);
for ii=2:length(x)
p=x(ii-1)-ii+1;
if (all(x~=p) && p>0)
x(ii)=p
else
x(ii)=x(ii-1)+ii-1
end
end

Categories

Find more on Startup and Shutdown in Help Center and File Exchange

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!