3728. Stable Subarrays With Equal Boundary and Interior Sum

You are given an integer array capacity. A subarray capacity[l..r] is considered stable if: - Its length is at least 3. - The first and last elements are each equal to the sum of all elements strictly between them (i.e., capacity[l] = capacity[r] = capacity[l + 1] + capacity[l + 2] + ... + capacity[r - 1]). Return an integer denoting the number of stable subarrays. Example 1: Input: capaci