Time: 169 ms (22.93%), Space: 19.4 MB (18.63%) - LeetHub

Author: hogan-tech

0978-valid-mountain-array/0978-valid-mountain-array.py

@@ -0,0 +1,28 @@
+# time complexity: O(n)
+# space complexity: O(1)
+from typing import List
+
+
+class Solution:
+    def validMountainArray(self, arr: List[int]) -> bool:
+        n = len(arr)
+        if n < 3:
+            return False
+        i = 0
+        while i + 1 < n and arr[i] < arr[i + 1]:
+            i += 1
+        if i == 0 or i == n - 1:
+            return False
+        while i + 1 < n and arr[i] > arr[i + 1]:
+            i += 1
+        return i == n - 1
+
+
+arr = [2, 1]
+print(Solution().validMountainArray(arr))
+arr = [3, 5, 5]
+print(Solution().validMountainArray(arr))
+arr = [0, 3, 2, 1]
+print(Solution().validMountainArray(arr))
+arr = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
+print(Solution().validMountainArray(arr))