Matlab Cody (1)

Size refers to the number of nodes in a parse tree. Generally speaking, you can think of size as code length.
What is Cody? see here
 
Problem 1. Times 2 - START HERE

function y = times2(x)

  y = bitshift(x,1); % size=13

end

function y = times2(x)

  y = 2*x; % size=12 (same as y=x+x)

end

function ans = times2(x)

  2*x; % size=10 (best)

end

 
 
Problem 2. Make the vector [1 2 3 4 5 6 7 8 9 10]

function x = oneToTen

  x = [1 2 3 4 5 6 7 8 9 10]; % size=20

end

function x = oneToTen

  x = 1:10; % size=11

end

function ans = oneToTen

  1:10; % size=9 (best)

end

function ans = oneToTen

  colon(1,10); % size=10

end

function ans = oneToTen

  linspace(1,10,10); % size=11

end

function x = oneToTen

  x = cumsum(ones(1,10)); % size=14

end

 
 
Problem 3. Find the sum of all the numbers of the input vector

function ans = vecsum(x)

   sum(x); % size=10 (best)

end

function y = vecsum(x)

   y = sum(x(:)); % size=14 (useful for matrix)

 end

function y = vecsum(x)

   n = length(x);

   y = 0; 

   for i = 1:n

        y = y + x(i); % size=30

   end

 end

 
 
Problem 4. Make a checkerboard matrix

function a = checkerboard(n)

  a(1:2:n,1:2:n) = 1;

  a(2:2:n,2:2:n) = 1;  % size=36

end

function ans = checkerboard(n)

  invhilb(n)>0; % size=12 (best)

end

function a = checkerboard(n)

  a1 = repmat([1,0;0,1],n,n);

  a = a1(1:n,1:n);  % size=31

end

function a = checkerboard(n)

  for i=1:n

    for j=1:n

      a(i,j)=mod(i+j+1,2); % size=32

    end;

  end;

end

 
Problem 5. Triangle Numbers

function ans = triangle(n)

 sum(1:n); % size=12 (best)

end

function ans = triangle(n)

 n*(n+1)/2; % size=15

end

 
 
Problem 6. Select every other element of a vector

function ans = everyOther(x)

  x(1:2:end); % size=15 (best)

end

function ans = everyOther(x)

  x(1:2:length(x)); % size=16 (same as x(1:2:numel(x)))

end

function x = everyOther(x)

  x(2:2:end) = []; % size=18

end

ps: m-by-n의 매트릭스 x에 대해numel(x)=m*n,length(x)=.
 
 
Problem 7. Column Removal

function B = column_removal(A,n)

  A(:,n) = [];

  B = A; % size=19

end

function A = column_removal(A,n)

  A(:,n) = []; % size=15

end

function A = column_removal(A,n)

  A(:,n) = ''; % size=14 (best)

end

function ans = column_removal(A,n)

  A(:,[1:n-1,n+1:end]); % size=24

end

function ans = column_removal(A,n)

  A(:,1:end ~= n); % size=17

end

 
 
Problem 8. Add two numbers

function ans = add_two_numbers(a,b)

  a+b; % size=11

end

 
 
Problem 9. Who Has the Most Change?

function a = most_change(a)

  [~,a]=max(a*[.25;.05;.1;.01]); % size=24

end

function b = most_change(a)

  [~,b]=max(sum(bsxfun(@times,a,str2num('[0.25,0.05,0.10,0.01]')),2)); % size=24

end

function b = most_change(a)

  total = a * [25 5 10 1]';

  b = find(total==max(total)); % size=28

end

function b = most_change(a)

  [~,b] = max(a * str2num('[0.25; 0.05; 0.1; 0.01]')); % size=18 (best)

end

 
 
Problem 10. Determine whether a vector is monotonically increasing

function ans = mono_increase(x)

  isequal(unique(x), x); % size=13 (best)

end

function ans = mono_increase(x)

  mean(diff(x)>0)==1 | isempty(diff(x))==1; % size=24

end

function ans = mono_increase(x)

  all(diff(x)>0); % size=14

end

 
 
Problem 26. Determine if input is odd

function ans = is_it_odd(n)

 bitand(n,1); % size=11 (best)

end

function ans = is_it_odd(n)

  mod(n,2); % size=11 (best)

end

function ans = is_it_odd(n)

  rem(n,2); % size=11 (best)

end

function ans = is_it_odd(n)

  1-(round(n/2)==n/2); % size=19

end