Oct 30

2024-10-October-LeetCoding-Challenge/Minimum Number of Removals to Make Mountain Array.py

@@ -0,0 +1,32 @@
+from typing import List
+
+
+class Solution:
+    def minimumMountainRemovals(self, nums: List[int]) -> int:
+        dpf = [1] * len(nums)
+        for i in range(len(nums)-1, -1, -1):
+            for j in range(i+1, len(nums)):
+                if nums[i] > nums[j]:
+                    dpf[i] = max(dpf[i], 1+dpf[j])
+        dpb = [1] * len(nums)
+        for i in range(len(nums)):
+            for j in range(i-1, -1, -1):
+                if nums[i] > nums[j]:
+                    dpb[i] = max(dpb[i], 1+dpb[j])
+        max_len = 0
+        for i in range(1, len(nums)-1):
+            if dpf[i] > 1 and dpb[i] > 1:
+                max_len = max(max_len, dpf[i]+dpb[i]-1)
+        return len(nums) - max_len
+
+
+def main():
+    nums = [1, 3, 1]
+    assert Solution().minimumMountainRemovals(nums) == 0
+
+    nums = [2, 1, 1, 5, 6, 2, 3, 1]
+    assert Solution().minimumMountainRemovals(nums) == 3
+
+
+if __name__ == '__main__':
+    main()

2024-10-October-LeetCoding-Challenge/README.md

@@ -32,7 +32,7 @@
 | October 27 | [1277. Count Square Submatrices with All Ones](https://leetcode.com/problems/count-square-submatrices-with-all-ones/) | Medium | Solved |
 | October 28 | [2501. Longest Square Streak in an Array](https://leetcode.com/problems/longest-square-streak-in-an-array/) | Medium | Unsolved |
 | October 29 | [2684. Maximum Number of Moves in a Grid](https://leetcode.com/problems/maximum-number-of-moves-in-a-grid/) | Medium | Solved |
-| October 30 | []() |  |  |
+| October 30 | [1671. Minimum Number of Removals to Make Mountain Array](https://leetcode.com/problems/minimum-number-of-removals-to-make-mountain-array/) | Hard | Unsolved |
 | October 31 | []() |  |  |
 
 
@@ -41,4 +41,4 @@
 | ---    | --- | --- | --- |
 | Easy   | 2 | 2 | 0 |
 | Medium | 24 | 14 | 10 |
-| Hard   | 3 | 2 | 1 |
+| Hard   | 4 | 2 | 2 |