LeetCode/kt/shortest-subarray-with-or-at-least-k-ii.kt

class Solution {
    private data class Window(val bits: IntArray, var left: Int) {
        fun updateBits(
            number: Int,
            d: Int,
        ) = bits.indices
            .filter { number.shr(it).and(1) != 0 }
            .forEach {
                bits[it] += d
            }

        fun toInt(): Int =
            bits
                .mapIndexed { index, it ->
                    when {
                        it != 0 -> 1.shl(index)
                        else -> 0
                    }
                }
                .reduce(Int::or)

        fun update(
            nums: IntArray,
            k: Int,
            right: Int,
        ): Int {
            updateBits(nums[right], 1)

            var minLength = Int.MAX_VALUE
            while (left <= right && toInt() >= k) {
                minLength = listOf(minLength, right - left + 1).min()

                updateBits(nums[left], -1)
                left += 1
            }

            return minLength
        }
    }

    fun minimumSubarrayLength(
        nums: IntArray,
        k: Int,
    ): Int {
        val window = Window(IntArray(32), 0)

        return nums.indices
            .map {
                window.update(nums, k, it)
            }
            .filter { it < Int.MAX_VALUE }
            .minOrNull() ?: -1
    }
}