LeetCode/kt/put-marbles-in-bags.kt

class Solution {
    fun putMarbles(
        weights: IntArray,
        k: Int,
    ): Long =
        weights
            .zip(weights.drop(1))
            .map { (w1, w2) -> (w1 + w2).toLong() }
            .sorted()
            .let { pairs ->
                (0..k - 2)
                    .map { i ->
                        weights.size - 2 - i to i
                    }.sumOf { (i, j) ->
                        pairs[i] - pairs[j]
                    }
            }
}