```var acc = 0 val order = IntArray(a.size) { ...

# announcements

[jimn]

var acc = 0
val order = IntArray(a.size) {
    acc += a[it].size
    acc
}

is there a more succinct accumulator array creation than this?

[jimn]

vargs.asIterable().foldIndexed(0 to IntArray(vargs.size)) { vix,(acc, avec), vec ->
            acc.plus(vec.size).let { size -> size to avec.also { avec[vix]=size}   }        }

this seems more fp-ish but I'm going to guess the instruction count is a little higher this way.

[natpryce]

(0 until a.size).map { a[it].size }.toIntArray()

[jimn]

as it happens i noticed im also using the accumulator below that code.

[jimn]

im also not a fan of temp List<Int> .