does `minBy` actually give a reference to original object I

Question

does `minBy` actually give a reference to original object I do `lowest = lowest next` in my code above does it actually move the `head` of the list stored in `lists`

diesieben07 · Answer

Objects work by references you are never actually working on the object only a reference to it

warriorprincess · Answer

Okay so its like pointers in c++ If I manipulate `lowest` here it will change in the original array too

diesieben07 · Answer

No it s not like pointers ```val x = MyObject x holds reference to that object val y = x y is set to the same value as x i e the reference to the object ```

diesieben07 · Answer

Everything is pass by value but you are not passing objects you are passing references

warriorprincess · Answer

going with your example `val x = 9 var y = x y = 8`

warriorprincess · Answer

obviously x doesn t become 8

diesieben07 · Answer

Yes gt Everything is pass by value

warriorprincess · Answer

okay yeah that makes sense i was just wondering how this LL works in such a scenario

warriorprincess · Answer

```class ListNode var `val` Int = 0 var next ListNode = null ```

diesieben07 · Answer

What do you mean by LL

warriorprincess · Answer

linkedlist sorry

warriorprincess · Answer

```var head ListNode head = head next```

warriorprincess · Answer

I guess this works because `head` is simply being overwritten

diesieben07 · Answer

You are storing a new value in `head` yes I am not sure why you think this would not work

warriorprincess · Answer

yeah sorry i was just confused i guess

warriorprincess · Answer

` var lowest = lists minBy it `val` Int MAX VALUE `

warriorprincess · Answer

``` var lowest = lists minBy it `val` Int MAX VALUE ```

warriorprincess · Answer

``` lowest = lowest next```

warriorprincess · Answer

this is what im trying to do

warriorprincess · Answer

but of course the original list stored in `lists` isn t affected by `lowest = lowest next`

diesieben07 · Answer

No of course not

warriorprincess · Answer

whats a good kotlin y way to to do this in your opinion

diesieben07 · Answer

Depends on your exactl use case really What is your end goal

warriorprincess · Answer

so we have a list of single linked lists

warriorprincess · Answer

the goal is to find the linked list with the smallest current HEAD value and then advance the head of said list to point to head next

warriorprincess · Answer

makes sense

diesieben07 · Answer

You are representing your linked list by just a pointer to the head which is a bit bad since thereby your linked list does not really have an identity You would have to get the index of the linked list with the lowest value and then update that index of the main list

diesieben07 · Answer

For that you can do `val lowest lowestIndex = lists withIndex minBy value index gt value whatever `

diesieben07 · Answer

And then `lists lowestIndex = lists lowestIndex next`

diesieben07 · Answer

But a much simpler and cleaner approach would be to write a `class LinkedList var head Node `

diesieben07 · Answer

Then you could do ```val listWithLowest = lists minBy it head val Int MAX VALUE if listWithLowest = null listWithLowest head = listWithLowest head next ```

warriorprincess · Answer

interesting

warriorprincess · Answer

`val lowest lowestIndex = lists withIndex minBy value index gt value whatever `

warriorprincess · Answer

whats happening in this line

warriorprincess · Answer

the docs for `withIndex` say Returns a lazy Iterable of IndexedValue for each element of the original array

warriorprincess · Answer

does it return some special version of List I mean minBy still works on it

diesieben07 · Answer

`list withIndex ` turns a `List lt T gt ` into a `Iterable lt IndexedValue lt T gt gt ` The ` value index ` is a destructuring operation grabbing the actual value and it s index in the list out of the `IndexedValue`

warriorprincess · Answer

or is it some special collection with index too

diesieben07 · Answer

Yes

warriorprincess · Answer

alright so minBy works on Iterable lt IndexedValue lt T gt gt too

diesieben07 · Answer

Yes `minBy` is defined for `Iterable`

warriorprincess · Answer

Got it

warriorprincess · Answer

``` val lowest lowestIndex = lists withIndex minBy value index gt value `val` Int MAX VALUE ```

warriorprincess · Answer

apparently not nullable values are needed to destructure

warriorprincess · Answer

so i guess il need to check for nullness first then destructure it

diesieben07 · Answer

Oh right `minBy` is nullable Yes

warriorprincess · Answer

also it says `val` is not defined for `value`

diesieben07 · Answer

Yeah it s ` index value ` sorry

diesieben07 · Answer

You can also do `minBy it value val Int MAX VALUE ` if you don t like the destructuring

warriorprincess · Answer

got it