[ASSIGNMENT] Range number

Question

A list has the property of having a "range number".
A range number is calculated by finding the maximum possible total difference between any order of consecutive terms.

Write a function rangenum(N) where N is a list.

Test cases:
rangenum([2,3,2])
>>> 2
([2,3,2] is the case)
rangenum([1,2,3])
>>> 3
([1,3,2] is the arrangement)
New test cases:
rangenum([8,1,7])
>>> 13 ([8,1,7])

Good luck! Bonus: give the permutation of the list that returns its range number

Thanks for Challenge of the Day! My first ever!

Answer 1

My handpicked solutions per language:
https://code.sololearn.com/cLXlAL7sU5w0/?ref=app (ruby)
https://code.sololearn.com/ciTHGNXG7fCB/?ref=apphttps://code.sololearn.com/ciTHGNXG7fCB/?ref=app (python)
https://code.sololearn.com/cc2nKA6NKu9r/?ref=app (C++)
https://code.sololearn.com/c7lsmtE2dxAv/?ref=app (Java)
https://code.sololearn.com/cvDtzQpLd9k3/?ref=app (C#)
Other languages are welcome 😊😊

In simple English:
So basically for any array:
-take the difference of 2 consecutive elements.
-sum up such differences
Different permutations of the array produce different such numbers, hence find the maximum of such numbers
Hope you understand the challenge!

Answer 2

congo for challenge of the day @vengat ☺

⬜🌹🌹🌹🌹🌹⬜
🌹⬜⬜⬜⬜⬜⬜
🌹⬜⬜⬜⬜⬜⬜
🌹⬜⬜⬜🌹🌹🌹
🌹⬜⬜⬜⬜⬜🌹
🌹⬜⬜⬜⬜⬜🌹
⬜🌹🌹🌹🌹🌹⬜

//i'll give it a try soon ☺ //v. busy

Answer 3

I didn't get your requirements at all

Answer 4

I don't understand
Я не понял
🤔🤔🤔

Answer 5

https://code.sololearn.com/ciTHGNXG7fCB/?ref=app
Works as mentioned

Answer 6

Pegasus my try, will add permutation later by God's grace
EDIT: Permutation added, It works but it is inefficient
https://code.sololearn.com/c576UXBQ4FXr/?ref=app

Answer 7

Congrats for COTD 👍
Here's my try :
https://code.sololearn.com/c5SHhnm0awVB/?ref=app

Answer 8

Heja... I found a clear rule to build the optimal sequence:
a) sort sequence
b) first number beginning,first number end, 2nd number begunning, 2nd number end...

Here my python solution:

https://code.sololearn.com/c4Rd5c0cKM0q/?ref=app

Answer 9

Yes absolute difference.
If multiple, either retuen all or (recommended) return any one of them

Answer 10

@Tommy take the difference of consecutive elements and sum them up. Find the maximum possible number that can be formed by any permutation of that list this way

Answer 11

♻♠💻💻🎊 Thank you everyone for making SoloLearn this interesting. Enjoy!

Answer 12

Reviewing different solutions I discovered that many of them are incorrect. E.g. for set of numbers [4, 2, 3, 3] many solutions answer 3, but the correct answer is 4 (sequence -> 3, 4, 2, 3). So, I decided to write my solution. ))
Enjoy!
https://code.sololearn.com/cvDtzQpLd9k3/#cs

Answer 13

@andrej deserves every click!

Answer 14

i think not. the idea of most algorithms is good but not complete.
the problems I see are identical values in the middle.
a sequence with two identical consecutive numbers cant be the ptimum..
one of them must be rearranged to one end.

@Andrej.. it is your turn!

Answer 15

https://code.sololearn.com/c4Rd5c0cKM0q/?ref=app

Answer 16

Hello Ale,

what you say is correct. It was more a mathematical challenge.
But at least on sololearn the correctness of tha algorithm was not the main point.
Many answeres ( also my first attempt) had a suboptimal solution.
But if that was implemeted correctly for me it was ok.
Very few learners found a better algorithm (w.o proof if it is right).
So we additionally had a mathematical discussion.

This challenge very clearly shew:

programming knowledge is one thing - algorithm knowledge a completely other one.
On sololearn the stress is on first one.
So the mathematical part even now is not completely solved.
For beginners a wake-up-call, for Math-Geeks (I am not) a fun.

Answer 17

https://code.sololearn.com/c6quJKU265mk/?ref=app

Answer 18

So basically for any array:
-take the difference of 2 consecutive elements.
-sum up such differences
Different permutations of the array produce different such numbers, hence find the maximum of such numbers

Answer 19

Here's my try with JS. Solved, right? :)

https://code.sololearn.com/WSw7Tb273t1M/?ref=app

Answer 20

@morpheus :
a man like you ... level12(!),
cool as ice
cant be stopped by this babyface.
I am right ..am I?