From 1db0649431671e16ae1d4ce733db128a0e8006bc Mon Sep 17 00:00:00 2001
From: Matej Focko <me@mfocko.xyz>
Date: Thu, 31 Oct 2024 00:09:24 +0100
Subject: [PATCH] =?UTF-8?q?kt:=20add=20=C2=AB1671.=20Minimum=20Number=20of?=
 =?UTF-8?q?=20Removals=20to=20Make=20Mountain=20Array=C2=BB?=
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URL:	https://leetcode.com/problems/minimum-number-of-removals-to-make-mountain-array/
---
 ...mber-of-removals-to-make-mountain-array.kt | 38 +++++++++++++++++++
 1 file changed, 38 insertions(+)
 create mode 100644 kt/minimum-number-of-removals-to-make-mountain-array.kt

diff --git a/kt/minimum-number-of-removals-to-make-mountain-array.kt b/kt/minimum-number-of-removals-to-make-mountain-array.kt
new file mode 100644
index 0000000..e74de4c
--- /dev/null
+++ b/kt/minimum-number-of-removals-to-make-mountain-array.kt
@@ -0,0 +1,38 @@
+class Solution {
+    private fun longestIncreasing(nums: IntArray): IntArray {
+        val found =
+            IntArray(nums.size) {
+                1
+            }
+
+        nums.indices
+            .flatMap { i ->
+                (0..i - 1)
+                    .reversed()
+                    .map { j -> i to j }
+            }
+            .filter { (i, j) -> nums[i] > nums[j] }
+            .forEach { (i, j) ->
+                found[i] = listOf(found[i], 1 + found[j]).max()
+            }
+
+        return found
+    }
+
+    fun minimumMountainRemovals(nums: IntArray): Int {
+        val increasing = longestIncreasing(nums)
+
+        nums.reverse()
+        val decreasing = longestIncreasing(nums)
+        decreasing.reverse()
+
+        return increasing
+            .zip(decreasing)
+            .filter { (l, r) ->
+                l > 1 && r > 1
+            }
+            .minOf { (l, r) ->
+                nums.size - l - r + 1
+            } ?: nums.size
+    }
+}