kt: add «3011. Find if Array Can Be Sorted»

URL:	https://leetcode.com/problems/find-if-array-can-be-sorted/
Signed-off-by: Matej Focko <me@mfocko.xyz>

kt/find-if-array-can-be-sorted.kt

@@ -0,0 +1,46 @@
+class Solution {
+    private fun min(
+        x: Int,
+        y: Int,
+    ): Int = listOf(x, y).min()
+
+    private fun max(
+        x: Int,
+        y: Int,
+    ): Int = listOf(x, y).max()
+
+    private data class State(
+        val prevMax: Int,
+        val bitCount: Int,
+        val min: Int,
+        val max: Int,
+    ) {
+        val sortable: Boolean
+            get() = min >= prevMax
+
+        private fun getSegmentMaximum(
+            prevMax: Int,
+            min: Int,
+            max: Int,
+        ): Int =
+            if (min < prevMax) {
+                Int.MAX_VALUE
+            } else {
+                max
+            }
+
+        fun update(num: Int): State =
+            if (bitCount == num.countOneBits()) {
+                State(prevMax, bitCount, min(min, num), max(max, num))
+            } else {
+                State(getSegmentMaximum(prevMax, min, max), num.countOneBits(), num, num)
+            }
+    }
+
+    private fun getInitialState(num: Int): State = State(Int.MIN_VALUE, num.countOneBits(), num, num)
+
+    fun canSortArray(nums: IntArray): Boolean =
+        nums.fold(getInitialState(nums[0])) { acc, it ->
+            acc.update(it)
+        }.sortable
+}