solution.cpp

class Solution
{
public:
    int minimumMountainRemovals(vector<int> &nums)
    {
        int n = nums.size();
        vector<int> LIS(n, 1), LDS(n, 1);

        // Compute LIS up to each index
        for (int i = 0; i < n; ++i)
        {
            for (int j = 0; j < i; ++j)
            {
                if (nums[i] > nums[j])
                {
                    LIS[i] = max(LIS[i], LIS[j] + 1);
                }
            }
        }

        // Compute LDS from each index
        for (int i = n - 1; i >= 0; --i)
        {
            for (int j = n - 1; j > i; --j)
            {
                if (nums[i] > nums[j])
                {
                    LDS[i] = max(LDS[i], LDS[j] + 1);
                }
            }
        }

        int maxMountainLength = 0;

        // Find the maximum mountain length
        for (int i = 1; i < n - 1; ++i)
        {
            if (LIS[i] > 1 && LDS[i] > 1)
            { // Valid peak
                maxMountainLength = max(maxMountainLength, LIS[i] + LDS[i] - 1);
            }
        }

        return n - maxMountainLength;
    }
};