如何在Kotlin中对列表中的项进行分组和求和

val people = listOf(
    Person("Alice", 25),
    Person("Bob", 30),
    Person("Charlie", 25),
    Person("David", 30),
    Person("Eve", 25)
)

val groupedPeople = people.groupBy { it.age }

val sumByAge = groupedPeople.mapValues { it.value.size }

data class Person(val name: String, val age: Int)

fun main() {
    val people = listOf(
        Person("Alice", 25),
        Person("Bob", 30),
        Person("Charlie", 25),
        Person("David", 30),
        Person("Eve", 25)
    )

    val groupedPeople = people.groupBy { it.age }
    val sumByAge = groupedPeople.mapValues { it.value.size }

    println(sumByAge)
}

{25=3, 30=2}