Difficulty: Medium
Tags: LeetCode, Medium, Array, Hash Table, Prefix Sum, Sliding Window, leetcode-930, Two Pointers, O(n), O(1)

Problem

Given a binary array nums and an integer goal, return the number of non-empty subarrays with a sum goal.

A subarray is a contiguous part of the array.

Example 1:


Input: nums = [1,0,1,0,1], goal = 2

Output: 4

Explanation: The 4 subarrays are bolded and underlined below:

[1,0,1,0,1]

[1,0,1,0,1]

[1,0,1,0,1]

[1,0,1,0,1]

Example 2:


Input: nums = [0,0,0,0,0], goal = 0

Output: 15

Constraints:

1 <= nums.length <= 3 * 10⁴
nums[i] is either 0 or 1.
0 <= goal <= nums.length