1793. Maximum Score of a Good Subarray

Description

You are given an array of integers nums (0-indexed) and an integer k.

The score of a subarray (i, j) is defined as min(nums[i], nums[i+1], ..., nums[j]) * (j - i + 1). A good subarray is a subarray where i <= k <= j.

Return the maximum possible score of a good subarray.

 

Example 1:

Input: nums = [1,4,3,7,4,5], k = 3
Output: 15
Explanation: The optimal subarray is (1, 5) with a score of min(4,3,7,4,5) * (5-1+1) = 3 * 5 = 15. 

Example 2:

Input: nums = [5,5,4,5,4,1,1,1], k = 0
Output: 20
Explanation: The optimal subarray is (0, 4) with a score of min(5,5,4,5,4) * (4-0+1) = 4 * 5 = 20.

 

Constraints:

• 1 <= nums.length <= 105
• 1 <= nums[i] <= 2 * 104
• 0 <= k < nums.length

 

Solutions

Solution: Two Pointers

• Time complexity: O(n)
• Space complexity: O(1)

 

JavaScript

/**
 * @param {number[]} nums
 * @param {number} k
 * @return {number}
 */
const maximumScore = function (nums, k) {
  const n = nums.length;
  let left = k;
  let right = k;
  let minNum = nums[k];
  let result = nums[k];

  while (left > 0 || right < n - 1) {
    left === 0 || nums[right + 1] > nums[left - 1] ? (right += 1) : (left -= 1);
    minNum = Math.min(nums[left], nums[right], minNum);

    const score = (right - left + 1) * minNum;

    result = Math.max(score, result);
  }

  return result;
};