array

[spice tree]

I was given 2 arrays:
array1 = {6, 13, 18, 1, 9, 7, 16, 11, 2}
array2 = {4, 10, 5, 12, 3, 8, 14}
I have to move the values in the two arrays so that all even values are in array 1 and all odd values are in array 2. However I can only use the 2 given arrays and cant use any additional data structures(part of the assignment).
I know I have to use a for loop and inside it i need an if statement but for some reason im forgetting how I should write the if statement having not coded in a minute.

for(int i = 0; i < array1.length; i++) {
  int value = i;
}

This is what I have so far

[oak crown]

<@&987246399047479336> please have a look, thanks.

[spice tree]

I also know I will need a while loop but I need to figure out the if statement first

like for each value
get current value in array1 at index i
if the current value is odd then search array2 for the 1st even value to swap with the odd value

thats the psuedocode but I cant remember how to put it into code

[turbid fjord]

You can use modulus % to know if a value is odd or even.

[spice tree]

Oh I have forgotten all about %

how would I use it in this sense

like if (value != %)

or is it different

[turbid fjord]

Remember, what is modulus 🙂

Its definitions should remind you

[spice tree]

the remainder when dividing

so value %2

?

[turbid fjord]

yes

[spice tree]

or am I still missing something

[turbid fjord]

No, you are on the right track!

[spice tree]

ok do I need the !=

[turbid fjord]

Test , see what happens

        int a = 5;
        int b = 2;

        System.out.println(a % 2);
        System.out.println(b % 2);

[spice tree]

i get an odd number (1) for a
and even (0) for b

[turbid fjord]

Try construct an if statement based on a, and b above.

[spice tree]

if( a % 2) {
a = odd
}

something like that

?

[turbid fjord]

You need a comparator too

[spice tree]

boolean?

or like

|| b % 2

[turbid fjord]

yes, that yields an boolean

[spice tree]

ok

would i need to declare the boolean before the if statement

[turbid fjord]

if (value % 2 == 0)
if (value % 2 == 1)

[spice tree]

ahh I see

I think I get it

[turbid fjord]

So you cannot create a new array? You must use those you have correct?

[spice tree]

yeah correct

[turbid fjord]

That could be challenging 🙂

[spice tree]

after I write the if statement inside of it I have to search through array 2 for the first even value to swap with the odd value

which is a little confusing haha

I imagine maybe another for loop and create an index for array 2

but im not sure

[turbid fjord]

What I don't understand, what happens when them arrays do not have the same size, and you cannot move an odd number from the even array to the odd array due to the lack of space.

In your example above, they are not even

[spice tree]

Yeah I'm not really sure either, it's just what the assignment says

lemme snag a pic

[turbid fjord]

I see, if i calculated correctly, there are 6 odd numbers. So they fit perfectly in array2. So, array2 is doomed to be the odd array.

[spice tree]

Yes

[turbid fjord]

OK, so it is just to stimulate your brain cells.

[spice tree]

Yeah, its our first assignment back from summer break

so we are trying to remember arrays and such

but I hated arrays before the summer break LOL

[lime ruin]

you can't use a temporary array to keep track of all content in both array ?

[spice tree]

no

I am not allowed

they will dock me points

my professor is very specifc

[turbid fjord]

Mean proffessor 😛

I have to think myself on this

[spice tree]

yep 😭

maybe I dont need a for loop

either way I need to create another index for array 2

array 1 being i and 2 being j

just not sure how to go about it

then create a boolean and write a while loop probs

[lime ruin]

hmm

I need to try but if we assign all the content of 1 array in the other array; I believe we can arrive at some points

like say array2 now have all the contents, loop through it, if a particular index has an odd value, then add to array1

[spice tree]

I see

[lime ruin]

well no I don't think this will work because the array should be of fixed size

[turbid fjord]

Oh there are an easy take on this, if efficient is of no cocern, in terms of algorithm used ^^

[spice tree]

as long as the code stays in main

I cant like create methods

or such

[lime ruin]

the arrays given are predefined ?

[spice tree]

// Search array2 for 1st even value to swap with the odd value
create an index into array2 (j)
create a boolean named found and set to false
while (not at end of array2 && have not found even value)
if array2[j] is even
found = true
else
increment j
end while
I think this could work

but idk how to put it into code

this being in the if statement thats in the for loop

[turbid fjord]

There are multiple solution to this problem.
Telling mine would ruin the professors stimulated test.

Are you allowed to write methods?

[spice tree]

im assuming we can

just not required

[turbid fjord]

You can do it without, but it makes it easier if you do write them

[spice tree]

she never really says we cant

this is all she says about methods

[turbid fjord]

My take on this, keep it simple, at the cost of efficiency in terms of time complexcity :P, as it is not a requirement.

[spice tree]

mkay

so what should I do then

[turbid fjord]

I would create one main while loop, that will finish when all elements have been moved to the array1 and array2, basically complete!
In this loop, I would simply find (loop) the first index of an odd value in array1, and find (loop) the first index of an even value in array2.
Switch them!
Repeat

[spice tree]

with this I dont need a method right

this is in main?

[turbid fjord]

You dont need, but it makes it MUCH easier for you to think if you do.

yes in main

[spice tree]

what would go in the parenthesis right after the while loop

[turbid fjord]

abstract away code, give it a nice little method name, gives you extra brain cells to work with,

[turbid fjord]

For this solution, When do we know when we are complete?
You talk about the while loop condition?

[spice tree]

when all odds are in one and evens are in another

[turbid fjord]

and for this solution, when is that? When do we know "ohh, we cannot continue any longer".
You can create a boolean called "complete" that is false. Set it to true when you know it is done.

Im trying to be vauge as possible 😛

[spice tree]

oh so while complete is false if array2 at index whatever is even then complete is false and if array2 at index whatever is odd then complete is true

and increment?

[turbid fjord]

More like, when we search for an index with an even value in the array2 (odd array), but there are none.
Vice versa for array1 (even array).

This is why it is easier to make a method regarding the search for index part, like

int indexA = findFirstEvenIndexOf(someArray)
int indexB = findFirstOddIndexOf(someArray)

[spice tree]

gotcha

lemme try sum

ok so im actually trying this from a different approach because I think itll be easier for me, I think I almost have it but my while loop is off

Instead of putting them into 1 array im just swapping each number

for(int i = 0; i < array1.length; i++) {
  int value = i;
  if(value % 2 == 1) {
    int j = 0;
    boolean found = false;
    while(array2[j] != 0 && found) {
      if(array2[j] % 2 == 0) {
      found = true;
      }//close if
      else {
      j++;
      }//close else
    }//close while
    if(found == true) {
      array1[i] = array2[j];
    }//close if
  }//close if
}//close for

the indentation on here is a lil off

but you get it

[turbid fjord]

int value = i;
You are checking if index i is odd

int value = array1[i]

[spice tree]

oh

[turbid fjord]

Your while loop condition also need some love

[spice tree]

yeah im so bad at while loops

they are probs my worst thing

like figuring out conditions

I just cant I have no clue why

[turbid fjord]

You are almost there.

Think of when the while loop should stop. Which conditions are there.
One is for example when 'j' is out of bounds to array2 for example, and as long as an even value has NOT been found.

I gotta go to my bed now.
You can solve it, very close.

[spice tree]

kk thank you!

[turbid fjord]

Are you using intellij?

[spice tree]

No im using eclipse

[turbid fjord]

No matter, my question should have been more like, are you using a real IDE. Some guys in here use some weird school IDEs.
USE DEBUG! Set a breakpoint and step through your code and analyze the result. You will learn alot that way, and find them mistakes.

[spice tree]

debugger so grosss but yes Ill use it haha

thank you so much!

[turbid fjord]

np, nnight

[spice tree]

nightt