# 1671. Minimum Number of Removals to Make Mountain Array from bisect import bisect_left """ you may recall that an array 'arr' is a mountain array if and only if 'arr.length >= 3', there exists soome index 'i' with '0 < i < arr.length - 1' such that 'arr[0] < arr[1] <... < arr[i - 1]' and 'arr[i] > arr[i + 1] > ... > arr[length - 1]'. given an integer array 'nums', return the minimum number of elements to remove to make 'nums' a mountain array """ class Solution(object): def minimumMountainRemovals(self, nums): """ :type nums: List[int] :rtype: int """ def lis(nums): dp = [10**10] * (len(nums) + 1) lens = [0] * len(nums) for i, j in enumerate(nums): lens[i] = bisect_left(dp, j) + 1 dp[lens[i] - 1] = j return lens l1, l2 = lis(nums), lis(nums[::-1])[::-1] ans, n = 0, len(nums) for i in range(n): if l1[i] >= 2 and l2[i] >= 2: ans = max(ans, l1[i] + l2[i] - 1) return n - ans if __name__ == "__main__": obj = Solution() print(obj.minimumMountainRemovals(nums=[1, 3, 1])) print(obj.minimumMountainRemovals(nums=[2, 1, 1, 5, 6, 2, 3, 1]))