[FIXED] Improving Time Efficiency on two custom List in KOTLIN

Issue

There are two lists:

val listA:List<Amodel> 
val listB:List<Int>


data class Amodel(val id:Int,var isUsed:Boolean=false)

Need to update listA isUsed =true based on the int id of the listB

What I'm doing now:

listB.foreach(){
//here i'm updating but it's taking too much time w.r.t time efficiency.
}

any GOOD solution.

Note list size is 500k+ for simulation

Solution

This might be slightly faster when the lists are huge:

val lookup = listB.associateWith { true }
listA.forEach { it.isUsed = lookup[it.id] ?: false }

Possibly this is even faster, I'm not sure. Because it then only sets isUsed in the case it needs to be true:

val lookup = listB.associateWith { true }
listA.forEach { lookup[it.id]?.run { it.isUsed = true } }

Answered By - Ivo Beckers
Answer Checked By - Dawn Plyler (JavaFixing Volunteer)