1671_Minimum_Number_of_Removals_to_Make_Mountain_Array.js

/**
 * @param {number[]} nums
 * @return {number}
 */
var minimumMountainRemovals = function(nums) {
    const n = nums.length;
    const left = Array(n).fill(1);
    const right = Array(n).fill(1);

    for (let i = 1; i < n; ++i) {
        for (let j = 0; j < i; ++j) {
            if (nums[i] > nums[j]) {
                left[i] = Math.max(left[i], left[j] + 1);
            }
        }
    }

    for (let i = n - 2; i >= 0; --i) {
        for (let j = i + 1; j < n; ++j) {
            if (nums[i] > nums[j]) {
                right[i] = Math.max(right[i], right[j] + 1);
            }
        }
    }

    let ans = 0;
    for (let i = 0; i < n; ++i) {
        if (left[i] > 1 && right[i] > 1) {
            ans = Math.max(ans, left[i] + right[i] - 1);
        }
    }

    return n - ans;
};