The score of an array is defined as the product of its sum and its length. For example, the score of [1, 2, 3, 4, 5] is (1 + 2 + 3 + 4 + 5) * 5 = 75. Given a positive integer array nums and an integer k, return the number of non-empty subarrays of n

countSubarrays.js

/**
 * @param {number[]} nums
 * @param {number} k
 * @return {number}
 */
var countSubarrays = function(nums, k) {
    let left = 0; // Left pointer of the sliding window
    let sum = 0; // Running sum of the current subarray
    let result = 0; // Stores the count of valid subarrays

    // Expand the window by moving the right pointer
    for (let right = 0; right < nums.length; right++) {
        sum += nums[right]; // Add the new element to the sum

        // If the score of the current subarray (sum * length) is >= k, skrink the window
        while (sum * (right - left + 1) >= k) {
            sum -= nums[left]; // Remove the leftmost element
            left++; // Move the left pointer forward
        }

        // The number of valid subarrays ending at 'right' is (right - left + 1)
        result += (right - left + 1);
    }

    return result; // Return the total count of valid subarrays
};