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Issues with Wolfram Challenges website and platform

Anonymous User
Posted 3 months ago
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For Wolfram Challenge, I am struggling more with your mistakes than with the challenges themselves.

You have problem with solved counter. If someone sends "wrong" solutions to the task before sending the correct solution - your counter counts all attempts, not only the right solution. Here is an example of two unsuccessful attempts at a solution plus one correct.

enter image description here

You have problems with the algorithm that compares the speed score. How do I know this? Simple, by testing.

enter image description here

And there is no doubt here. If you want, you can show your users a quicker solution than that. Put score 56.09 out of 100 on a pre-calculated solution which hardly makes any calculations...is a bit confident on your part.

PrimeGap[gap_ /; 
   EvenQ[gap] && gap > 0] := {{3, 5}, {7, 11}, {23, 29}, {89, 
    97}, {139, 149}, {199, 211}, {113, 127}, {1831, 1847}, {523, 
    541}, {887, 907}, {1129, 1151}, {1669, 1693}, {2477, 2503}, {2971,
     2999}, {4297, 4327}, {5591, 5623}, {1327, 1361}, {9551, 
    9587}, {30593, 30631}, {19333, 19373}, {16141, 16183}, {15683, 
    15727}, {81463, 81509}, {28229, 28277}, {31907, 31957}, {19609, 
    19661}, {35617, 35671}, {82073, 82129}, {44293, 44351}, {43331, 
    43391}, {34061, 34123}, {89689, 89753}, {162143, 162209}, {134513,
     134581}, {173359, 173429}, {31397, 31469}, {404597, 
    404671}, {212701, 212777}, {188029, 188107}, {542603, 
    542683}, {265621, 265703}, {461717, 461801}, {155921, 
    156007}, {544279, 544367}, {404851, 404941}, {927869, 
    927961}, {1100977, 1101071}, {360653, 360749}, {604073, 
    604171}, {396733, 396833}}[[gap/2]]

You have some crazy time limit of 3000 milliseconds for task. You definitely have time-consuming challenges. Even "Prime Gap" for my non-optimized code take near 11 sec = 11000 milliseconds

PrimeGap[gap_ /; EvenQ[gap] && gap > 0] := Module[
  {pgFind = False, pgCounter = 1, pgResult = {}},
  While[pgFind == False,
   pgCounter++;
   If[(Prime[pgCounter] - Prime[pgCounter - 1]) == gap, 
    pgResult = {Prime[pgCounter - 1], Prime[pgCounter]};
    pgFind = True
    , Nothing]
   ];
  pgResult
  ]

enter image description here

POSTED BY: Anonymous User
Answer
5 Replies
Anonymous User
Anonymous User
Posted 3 months ago

Look this "Texas Sharpshooter" picture from your calculation:

https://challenges.wolfram.com/challenge/texas-sharpshooter

I can come to the conclusion that there are possible problems in your function and I will have trouble to fight it.

enter image description here

enter image description here

This means you either have display problems because of the picture pixeling OR you have calculating problems and I will struggle with the accuracy of your floating point. Even only this opportunity stops me from solving this challenge. I'm tired of struggling with your bugs.

Solution is simple:

  1. Make all possible triangles from the points.
  2. Sort them.
  3. DeleteDuplicates.

And you have all the unique triangles

In[15]:= DeleteDuplicates@
 Map[Sort@# &, Permutations[{1, 2, 3, 4, 5, 6}, {3}]]

Out[15]= {{1, 2, 3}, {1, 2, 4}, {1, 2, 5}, {1, 2, 6}, {1, 3, 4}, {1, 
  3, 5}, {1, 3, 6}, {1, 4, 5}, {1, 4, 6}, {1, 5, 6}, {2, 3, 4}, {2, 3,
   5}, {2, 3, 6}, {2, 4, 5}, {2, 4, 6}, {2, 5, 6}, {3, 4, 5}, {3, 4, 
  6}, {3, 5, 6}, {4, 5, 6}}
  1. You make a function that calculates the perimeter of these triangles by their coordinates.
  2. You choose the smallest of these perimeters - these are the closest points.(What happens to your function if it meets two sets of three points that are the same distances one from each other?)
  3. You make a function that define the smallest circle that covers these three points. Here are some specific cases. The three points lie on a circle and not lie on the one circle.

And this algorithm is done in mind before you start writing the code. As I said, I do not write it, because I doubt that you have done it properly.

POSTED BY: Anonymous User
Answer

I experience similar issues with Wolfram Challenge. I intended to move on, but your commitment puts me on hold with that. By the way I doubt that Reddit will have any major influence regarding your concerns. The really active WL community is academic and small (compared to other languages and communities).

I have similar issues with the Wolfram challenges. I did not do an extensive investigation, but found errors in more than half of those that I tried, mostly centered about defective validation tests. I have communicated with tech support about the issues, and even sent code that would fix the problem in one case, but with no result.

The system is too easy to game. I think that the emphasis on speed and code size is misdirected. 40 years ago, these might have been real considerations, but now, understanding is much more important, and the feedback in this regard is minimal.

The challenges could be an effective training method, but not in its current form.

Dear, @Emil Enchev ! Welcome to Wolfram Community! Please make sure you know the rules:

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Wolfram Community highly values our members' feedback, thank you. But Wolfram Community encourages only friendly discussions and does not tolerate any comments of hostile nature, these were removed from your post and are not subject to any further discussion. For more direct conversation about Wolfram Challenges issues please contact Customer Support directly.

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Hi all,

Thank you for the feedback.

I worked on Wolfram Challenges and can offer some explanations.

Prime Gaps

The speed score is a metric that compares your solution's speed to the speed of our solution, which we use to compare answers. It's on a scale of 0 - 100, 50.00 means your solution was just as fast as ours, and the higher your score, the faster it is.

It just so happens that our solution for Prime Gaps makes use of cached tables, similar to your solution.

I agree this can come off as confusing. Essentially, you have a cached solution and yet the score we assign makes it feel suboptimal.

One potential fix is for us to use a less optimal (i.e. more procedural) solution to reward users like yourself for being clever. Another idea is to show the users our solution once they've successfully completed a challenge. The latter is an idea we've considered (and are still considering) but there are potential downsides to showing solutions (as well as upsides).

Texas Sharpshooter

I think the biggest issue here is the feedback we give when an answer is incorrect. We are aware that this is suboptimal and are working towards ways of fixing this.

  • Issue from OP

I have extracted the points from the graphics object pasted in the screenshot.

Distance between those 2 points:

In[16]:= EuclideanDistance[{0.25711737788963784`, -0.39693452786642736`}, {-0.030352070943268306`, -0.8225715177985533`}] // FullForm

Out[16]//FullForm=0.5136200260998158`

Diameter of the disk:

In[20]:= BoundingRegion[{{-0.030352070943268306`, -0.8225715177985533`}, {0.25711737788963784`, -0.39693452786642736`}, {-0.030352070943268306`, -0.8225715177985533`}}, "MinDisk"]

Out[20]= Disk[{0.113383, -0.609753}, 0.25681]

In[21]:= 2*Last[%] // FullForm

Out[21]//FullForm=0.5136200260998158`

So we can see that OP is indeed correct that the 2 points lie on a diameter. I think this means the rasterization is not 100% pixel perfect.

  • Grading this challenge

In this challenge, we are aware that there will be floating point error. The grader we use takes this into account and has a built in tolerance. In this case we require each float from submitted and our solution to be within 10^-8. of each other. This is well within the margin of floating point error.

We see (in the admittedly hard to read feedback) that the radius submitted was 0.364... and ours was 0.360.... We can also see the centers are different and so these disks are indeed distinct.

Again, the real issue here is the feedback we give. It's clear we need to, at the very minimum, make it readable and have a way of accessing the entire input without the ShortForm. Perhaps we should also explicitly explain the margins of error we allow. And by the way, your idea of graphical feedback is fantastic, thank you.

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