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HW2 LOGIC!!!!

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enricomaria.follega (1460 points)
8 18 29
in HW2 by (1.5k points)
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I started to code it about 2 days ago and i'm stuck. The score of the code i wrote does not match with the score i should expect. I didn't get why since i've followed the description line by line.

I continue to read the description again and again but doubts remains.

According to the description:

      "Ogni elemento della sequenza di A viene confrontato con l'elemento corrispondente della sequenza di B" ->  that is   A - B, which is different from B - A. Then

      "se la differenza fra il valore di A e il valore di B è inferiore o uguale ad un parametro k" ... "viene assegnato un punto al concorrente che ha generato il valore più alto"; ->      A - B il punto va a max(A,B)

      "se la differenza fra il valore di A e il valore di B è superiore a k" ... "viene assegnato un punto al concorrente che ha generato il valore più basso" ->      A - B il punto va a min(A,B)

      "se la differenza fra il valore di A e il valore di B è" ... " pareggio" ->      that is diff=0  "a nessuno"

Than at the end of the game if there is a tie between players

       "vince il giocatore che ha generato la sequenza con somma totale dei valori inferiore." ->      that is  min(SumSequenceOfA, SumSequenceOfB)

We know how it works so i will not stop on all the details comparing letters by letters but just on the points where i have doubts.

- First example, if we compare the first and the second player we should make (A - B) -> (a - c), the difference between the first and the subsequent player. The professor wrote (c - a) and then wrote the difference between (a - c)= -2. that's fine i guess indeed the expected result is the same with the one i have,   

- Second example, mine is completely wrong i get [2, 1, 0], but again he wrote (c - a) this time with (c - a) result =2 though and it's different to (a - c)= -2 so the score should go to player 1 not to player 0; between plr0 and plr2 the score should go to plr2, the result is (-2, 0, 2); and between plr1 and plr2 to plr2 again since the result is (0, 2, 2). Expected Leaderboard (0, 2, 1).

Also for the other 2 examples i get (2, 0, 1) and (2, 1, 0) respectively whereas the Expected Leaderboard should be (0, 1, 2) and (1, 2, 0).

  Don't know maybe i didn't get something. Do you have suggestions?

checking the other example like ["aaa", "bbb", "ccc", "ddd", "eee"] k=5 and k=3, i get in both (4, 3, 2, 1, 0) as result. of course are subsequent letters (a-b) so it will always be negative, modifing k from 5 to 3 nothing should change, still i don't get why his result is different.
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2 Answers

andrea.sterbini (207920 points)
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have you computed the absolute value of the difference or just the difference?
e
enricomaria.follega (1460 points)
8 18 29
by (1.5k points)
Should i take the absolute difference between the two? I guess that in my code i get the absolute value, i'm not sure though.

In my code:

   it subtracts ( A - B ), it just take a and b and then subtracts them, than according to the result (<=, > k ), it goes back to the list of the combinations and picks the greatest/smalles value, then according to that value the score is assigned. After the game it checks the two scores and state who won.

of course though doing ( B - A ) is not the same. i get the opposite result.

suggestions?
KilianS (3590 points)
7 10 27
by (3.6k points)
there is the abs() function, which basically returns the difference(absolute value).

in other words: abs(a-b) would be the same as abs(b-a)
e
enricomaria.follega (1460 points)
8 18 29
by (1.5k points)

HONOR TO MY SAVIOR!!!!!!!!!!!!!!!

i didn't know of that formula. yeah that was the mistake. i also thought the difference was absolute before, i must have been drunk.

How do i give you points?!?!??! 

i will create fake accounts to give you other points too winklaughdevil

Thanks, really mate.yes

e
enricomaria.follega (1460 points)
8 18 29
by (1.5k points)

write the same comment as new answer or i will give the point to the professor yes

Luigi Pizza (6120 points)
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So, the homework can be divided into two different parts: comparing the sequences and comparing the result of each sequence. For simplicity's sake let's say that we have 

A = ['aacda'],   B = ['caaad'],   k = 2

we take the map with function ord, obtaining:

A = [97,97,99,100,97],   B = [99,97,97,97,100]

Now we compare one to one each element of these lists:

A[0]-B[0],  A[1]-B[1],  A[2]-B[2], ...

getting:

-2, 0, 2, 3, -3

Based on how we have structured the subtraction: 

A will get a point if the difference is: 0 < A[x]-B[x] <= 2 or A[x]-B[x] <= -2

B will get a point if the difference is: -2 < A[x]-B[x] <= 0 or A[x]-B[x] >= 2

In this case we have that A will get 2 points and B will get 2 points. We have a tie.

At this point we sum up all the ords of the two lists above, but their result is the same:

 image

So we compare the 2 sequences:

A>B

So A wins.

I can't really tell you what you did wrong in your code, you can go down in any of these steps, just ckeck, either with the debugger or a lot of prints for the error in simple cases, hopefully you'll find it before midnight

andrea.sterbini (207920 points)
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why don't you give him just your code? angry

e
enricomaria.follega (1460 points)
8 18 29
by (1.5k points)

testing out your test (['aacda', 'caaad'], k=2) i get as result B winner. which should be the correct one, by hand calculation too.

the passages in my code looks correct to me, dunno. :|

Prof what if i send you the code and you fix it for me? i would go to have lunch :D.     It's just logic now 1+2, codeing is done, should be at least.