The problem is to check if sequence is palindrome using Brainfuck.
input is a sequance of numbers
output 0 if it is not palindorme, else 1.
I have one idea:
Say, we have sequance 1 2 3 2 1. We can memorise first cell from our array in variable(do this using operation '!'),
then change 1 to 0(do this using operation '0'),array will be 0 2 3 2 1,
then we go to the end of array until we meet 0 (do this using
'>[>]'),
then we take number from variable and get sequance 0 2 3 2 1 1.
Next step should be to compare two last numbers, if they are equal continue algo from begining else do something...
I do not know how to implement last step.
please excuse me if I won't write the entire program in brainfuck,
This is the main idea:
Read input (pointer should be at last character afterwards)
memorize character
Set value to 0
Go to first [<]
Compare to memorized character (see Brainfuck compare 2 numbers as greater than or less than)
If not equal, print 1
If the next (>) cell array is 0, print 0
Move to pointer to end [>]
Go back to step 2
Related
A boolean vector has been created based on some rule and we need to identify the indices where the rule holds for 2 observations in a row. The following code does that
indices:0101001101b
runs:{0 x\x}"f"$;
where 2=runs indices
Could you please help me understand how the scan operator is used in the definition of the runs function? Appreciate your help.
It's using this special shorthand commonly used in calculating exponential moving averages: https://code.kx.com/q/ref/accumulators/#alternative-syntax
So {0 x\x} is equivalent to:
q){z+x*y}\[0;indices;indices]
0 1 0 1 0 0 1 2 0 1
What this is doing is essentially using the booleans as an on/off switch (via the boolean multiplication) for the rolling sum. It adds (z+) until it hits a negative boolean in which case the rolling sum resets back to zero.
In english: nextValue + [currentValue (starting at 0) * nextValue]
When nextValue is 1, 1 gets added. When nextValue is 0 the result is zero (resetting the rolling sum).
Something like this can achieve the same thing, though no less easy to read at a glance (and using two scans instead of one):
q){s-maxs not[x]*s:sums x}indices
0 1 0 1 0 0 1 2 0 1i
Terry has answered your question about how runs works.
Comparing adjacent items is common. You might prefer to use the prior keyword. Certainly easier to see what it is doing.
q)where (and) prior indices
,7
Create a Racket procedure compute_pos that reads numbers from the keyboard until 0 is read, count how many positive numbers are read, and also compute the sum of only positive numbers, and display the count and the sum of positive numbers in different lines. Note that 0 is not included in the computations.
For example, if user enters:
3
6
-4
12
15
-9
-24
4
-3
-5
1
0
then your procedure should print
positive count: 6
positive sum: 41
You need to utilize “display” procedure to display the count and the sum, and also utilize “read” procedure to keep reading the next number from the keyboard.
I don't even know where to start so thanks for any help.
I need some help of solving that issue: I have 5 different voltage values that change every single tick time - that mean every single moment. I need to sort them and after they been sorted I want to go to another matrix(like this one at the bottom) and to pull out(read) specific column from it, for every state pre define(timing that I am designing..) That mechanism change every single states/moment. How can I do this ?
The Matrix look like(and could be greater...):
0 0 0 1 1 1...
0 1 1 0 0 1...
1 0 1 0 1 0...
1 1 0 1 0 0...
.. .. .. .. .. ..
Thanks, Henry
I am not sure I understood it correctly. So I will edit my answer after you make your question a bit more clear.
I see two separate things:
Reading 5 voltage values which change at each step. You want to sort these values. To do this you can use the sort function of matlab. It is really easy to use and you can look at it here.
This is the part I didn't understand well. After sorting the voltage readings what do you want to do with the matrix ? If you want to access just a specific column of the matrix and save it in a variable you can do it in this way. Let's assume you have a matrix A which is N x N, if you want to access the 10th column of the matrix and store it in a variable called column10 you will do something like: column10 = A(:,10)
I hope this will help you but let me know if this is what you wanted and I will edit my answer according to it.
Fab.
I am trying to generate prime numbers recursively using the previous primes. 2 is a prime by default and each time I keep adding 1 to the next number and divide by the previous primes, eg 2+1=3 so i check that 2 does not divide 3 so 3 is prime so i store 2 and 3 so far, next would be 3+1=4, i would use my current prime list 2 and 3, and see that 2 divides 4 so it does not go into the list then i continue with 4+1 and so forth all the way up to n. The key thing is dividing by the previous primes each time and if you reach a prime the list is updated. Please check my program to see what i am doing wrong.
this is my program so far but I am just getting 3 and 962, i want it update the list and refer back to it each time for the loop so i can use mod(2+numba,primlist) each time:
n=960;
primlist=[];
for numba=2:n
if mod(2+1,2)~=0
primlist=2+1;
end
if mod(2+numba,primlist)~=0
primlist=[primlist;2+numba];
end
end
primlist
You are initializing your primlist again and again. Do not do that. I am making as less modifications to your code to make it run correctly. The logic is essentially correct. You just need to initialize primlist outside.
n=960;
primlist=2;
for numba=1:n %Changed 2 to 1
if mod(2+numba,primlist)~=0
primlist=[primlist;2+numba];
end
end
primlist
I have a line of code in matlab for which i am selecting a subset of a matrix:
A(3:5,1:3);
Now i want to adapt this line, to only select rows for which all three values are larger than zero:
(A(3:5,1:3) > 0);
But apparently i am not doing this right. How do i select part of the matrix, and also make sure that only the rows (for which all three values are) larger than zero are selected?
EDIT: To clarify: lets say that i have a matrix of coordinates called A, that looks like this:
Matrix A [5,3]
3 4 0
0 1 0
0 3 1
0 0 0
4 8 7
Now i want to select only part [3:5,1:3], and of that part i only want to select row 3 and 5. How do i do that?
The expression:
A(find(sum(A(3:5,:),2)~=0),:)
will return only the rows of A(3:5,:) which have a row-sum not equal to zero.
If you had posted syntactically correct Matlab it would have been easier for me to cut and paste your test data into my Matlab session.
I'm modelling this answer off of A(find( A > 0 ))
distances = pdist(find( pdist(medoidContainer(i,1:3)) > 0 ));
This will give you a vector of values in the distances variable. The reason the pdist(medoidContainer(i,1:3) > 0) does not work is because it first, finds the indices specified by i,1:3 in medoidContainer. Then it finds the indices in medoidContainer(i,1:3) that are greater than 0. However, since medoidContainer(i,1:3) and pdist now likely have different dimensions, the comparison does not give the right indexes.