source: https://leetcode.com/problems/number-of-zero-filled-subarrays/description/ Number of Zero-Filled Subarrays Given an integer array nums, return the number of zero-filled subarrays. A subarray is a contiguous non-empty sequence of elements within an array. Example 1: Input: nums = [1,3,0,0,2,0,0,4] Output: 6 Explanation: There are 4 occurrences of [0] as a subarray. There are 2 occurrences of [0,0] as a ...