Merge values in map kotlin

Question

I need merge maps mapA andmapB with pairs of \"name\" - \"phone number\" into the final map, sticking together the values for duplicate keys, separated

Answer 1

Here is my approach with universal map-merging helper function:

fun  Pair, Map>.merge(merger: (V?, V?) -> R): Map {
    return (first.keys.asSequence() + second.keys.asSequence())
            .associateWith { merger(first[it], second[it]) }
}

fun main() {
    val mapA = mapOf("Emergency" to "112", "Fire department" to "101", "Police" to "102")
    val mapB = mapOf("Emergency" to "911", "Police" to "102")
    val result = (mapA to mapB).merge { a, b -> 
            listOf(a, b).filterNotNull().distinct().joinToString(",", "(", ")") }
    println(result)
}

Output:

{Emergency=(112,911), Fire department=(101), Police=(102)}