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's my solution:

val result = (mapA + (mapB - mapA.keys)).mapValues {
    (setOf(it.value) + mapB[it.key]).filterNotNull().joinToString()
}

It creates a map of A plus the values from B that are not in A. Then it maps all values to a set and adds the value from B to that set, ultimately removing all null values from the set and transforming it into a list, which you can use to create the desired output format.