Week 8

 This week I went over some interesting videos. One video was from the playlist I mentioned in a previous blog and it was titled "Will it stop?". The video is about a problem that asks you to determine if the code will terminate(stop).

To determine if it will stop we can mentally plug in numbers. n being less than or equal to 1 will stop the code so the first number we can try is 2. 

2 goes in the loop and we get if ( 2%2 =0 )(true) 

2/2 =1  and the code stops. So if n is 2 the code will stop. 

3 goes in, 

if (3%2 =0) (false)

 3*3+3=12

 if (12 %2=0) (true)

12/2 = 6 n

if (6%2 =0) (true) 

6/2 =3 and we get a loop. 

we plug in 4 we get if (4%2=0) (true)

4/2 =2 and we know 2 stops the code.

So from what we see it looks like even numbers will stop the code but if we look at the number 6 it turns out that is not true and we can see if when we can see that when we plug in 3. But when we plug in 8 it stops the code, which makes it look like that powers of 2 are what stops the code.(illustration of each number that work from 1-10 and the rules of the code below from the video)

 
Cool fact that a very similar equation at the university of Warsaw(below) 

This equations is said take any positive n and as it says has been verified with values up to 57646x10^18.


My code that goes through 1-16 for the first equation. In the video we decided that we can check if n is a power of two by doing n xor n-1 & n = n, which is why I have that.


ex. they use this in the video 16 (0b1000) 16-1=15(0b0111) 1000 xor 0111 = 1111 & 1000 = 1000 (true)


Also did first 100 for the second code the one that is at the university of Warsaw.(unfortunately some of them go off screen).



All of them end with a 1 so it is valid for the first 100 that I have tested.

video: https://www.youtube.com/watch?v=c4nJd0aC7sA&list=PLyqSpQzTE6M9p9pKxFGpskf4voY45T2DZ&index=6

Comments

  1. Genaro RiveraOctober 28, 2022 at 9:45 PM

    I recently started coding this semester, so the only time I dealt with an infinite code is with a while loop function which you can easily eyeball and tell if it will go on forever. So, this was fascinating seeing that code will be so complex that you may need to use these techniques to see if it will end which has obvious applications.

    ReplyDelete
  2. EricaNovember 4, 2022 at 8:46 AM

    Very interesting one indeed. Nice work!

    ReplyDelete

Post a Comment

Popular posts from this blog

Week 9

Image
 Today I looked at some interesting videos of some leetcode videos, which use problems that show up at coding interviews. I watched a guy who was prepping for interviews by running through these problems and talking about them. First Video was about locating islands. (pic of the instructions below) So hopefully you can see how the first input has only one island because all the ones are surrounded by zeros. It's kinda hard to see at first but it helped when he points out why in the video. He talks about the problem and comes up with a pretty straightforward solution. He says he will use a breadth first search(BFS), which I've done a bit of research on before in my week 6 of last years blog. Breadth first search when used on binary search trees takes a node and searches all of its nodes, so I can see how it can apply to this problem. Breadth first search will take one island(1) and search all the 1s connected, which is an island, so when it can't find anymore it means there ...
Read more

Week 10

Image
 This week I found an interesting problem that was exactly like a problem I did in my class this semester, csc 230, but instead of mips I did it in java. The problem is fizzbuzz where you take a number and if the number is a multiple of 3 print fizz and it its a multiple of 5 print buzz and if its a multiple of both print fizzbuzz. There are two method one(first one) is the one that was in a video where I discovered the problem and the second one is me doing it the way I thought of. The problem was pretty easy but the way it did intrigued me because It was different than mine his felt much more clever than mine. What he does is creates variable fizz and buzz so when fizz equals 3 and buzz equals 5 we reset and add to the arraylist but its cool that he does this by using variables to keep track of the fizz and buzz. So fizz for the first 10 will look like this 0,1,2,0,1,2,0,1,2,0,1 for buzz its 0,1,2,3,4,0,1,2,3,4,0 at all zeros after the first zero will add the respective word....
Read more

Week 11

Image
 Today I did another leetcode problem. Like last week I found a similar problem to one I've done in class but with a different language but instead of mips this time it is in C++. I'm starting to think my 240 teacher was making us do these problems on purpose haha... anyway, the problem this time is called valid parenthesis or matching brackets is what my 240 teacher called it. I knew the basic rundown of the problem and tried to code it. But to give a brief rundown we are checking if all brackets "("  or "{"  or "[" are closed correctly. Fortunately, I was able to directly translate the code for the most part, so we can see the tiny differences between c++ and java.  We see in the two pictures below that c++ looks a little different. In java we see the stack as new stack but in C++ #include stack and we dont need to new. In C++ the string as treated a char arrays so we dont need to do charAt in C++ they already are characters and in this respect i...
Read more