Mathematic logic question!

Question

I wont to fix my programm. I have a random array with 1 to 8 no repeat numbers. Not all arrays a good for my programm. Can you find anything can help? Remember that is an array....
***SLIDER PUZZLE ***
https://code.sololearn.com/Wiv9Z9z3L6Az/?ref=app

18732456 ok
32574861 ok
72643158 ok
68351472 ok
24185673 ok
51748632 ok
47623158 ok

18264537 wrong
75281346 wrong
12753486 wrong
13578462 wrong
61735284 wrong
38756241 wrong
76312845 wrong

Answer 1

I know this is a stupid idea but could you have an array of all the valid arrays. Then use a random number to select one of these arrays for the game?
It'll take a lot of time and not as clever but still works 😅

Answer 2

It's okay I have the solution
(thanks Burey for link)

I will explain:
let's say that we have 8 brothers ...
brother age 1......age 5 .....age 8

IF THE SUM ( BROTHERS AFTER ) IS EVEN
THE PUZZLE IS SOLVABLE

example: 47623158 is ok

4 has 3brothers after (231)
7 = 5.....................(62315) brother8 is bigger
6 = 4 (2315)
2 = 1 (1)
3 = 1 (1)
1 = 0
5 = 0
8 = 0
SUM = 3+5+4+1+1+0+0+0
SUM = 14
14 IS EVEN
PUZZLE IS SOLVABLE
so random 47623158 is ok

now I should write the code

Answer 3

@Alvaro it is an Array = [0,1,2,3,4,5,6,7]
there are 7 arrays ok and 7 wrong

Answer 4

@Burey if you try the program you'll understand

Answer 5

Thanks Burey

Answer 6

it is very important the position of any number in the array and all the 8 positions of numbers as a group

Answer 7

ok did some research
and found you some reading material :)

this refer to the game 15-puzzle where you have 15 tiles instead of 8
but the solution should be similar ;)

https://www.cs.bham.ac.uk/~mdr/teaching/modules04/java2/TilesSolvability.html

edit
also found this link (contains a function to check):
http://math.stackexchange.com/questions/293527/how-to-check-if-a-8-puzzle-is-solvable

Answer 8

no problem :)
i edited my last post, with another link

Answer 9

what are the rules for a bad positioning?

identify those and you can progress to tackle the problem

Answer 10

i tried it already, i just suck at it :p

anyway i understand that the problem is that some arrangments are unsolvable

is there a notable pattern for that?

Answer 11

Are the numbers in the second part individually wrong, or all of them as a whole?

Answer 12

Turn the number into a string. Otherwise you can't look at digits.

Separate characters into a list.

For every character, for every character after it, check if they are different. I you find doubles, abort. Otherwise return your number.