// Leetcode task solution: https://leetcode.com/problems/minimum-rounds-to-complete-all-tasks/description/
class Solution {
    fun minimumRounds(tasks: IntArray): Int {
        val map = tasks.toCountedMap()

        var rounds = 0
        map.forEach { entry ->
            val minRounds = minRounds(entry.value)
            if (minRounds == -1) {
                return -1
            } else {
                rounds += minRounds
            }
        }

        return rounds
    }

    private fun IntArray.toCountedMap(): Map<Int, Int> {
        val map = mutableMapOf<Int, Int>()

        for (task in this) {
            map[task] = (map[task] ?: 0) + 1
        }
        return map
    }

    private fun minRounds(tasksNumber: Int): Int {
        val rounds3 = tasksNumber / 3
        val residue = tasksNumber % 3
        return when {
            residue == 1 && rounds3 == 0 -> -1
            residue == 1 ||
            residue == 2 -> rounds3 + 1
            else -> rounds3
        }
    }
}