class Solution {
    fun maximumSubarraySum(
        nums: IntArray,
        k: Int,
    ): Long {
        var maximum = 0L

        var (l, r) = 0 to 0
        var runningSum = 0

        val seen = mutableMapOf<Int, Int>()
        while (r < nums.size) {
            val x = nums[r]

            val lastSeen = seen.getOrElse(x) { -1 }
            while (l <= lastSeen || r - l + 1 > k) {
                runningSum -= nums[l]
                l += 1
            }

            seen.put(x, r)
            runningSum += nums[r]

            if (end - begin + 1 == k) {
                maximum = listOf(maximum, runningSum).max()
            }

            r += 1
        }

        return maximum
    }
}