Had an interesting question today that I am still not sure how to approach:\n\nYou are given an array of positive/negative numbers that are not necessarily distinct. We have to return the number of contiguous subarrays that contain *at least one* of each number (i.e. **only** duplicates). \n\nExamples:\n\n```\n[0, 0, 0] => 3: first two 0s, second and third 0, and entire array\n[1, 2, 3] => 0\n[1, 2, 3, 3, 3, 2, 4, 1] => 4: [3, 3] (first), [3, 3] (second), [3, 3, 3], [2, 3, 3, 3, 2]\n[1, 2, 1, 2] => 1: only the entire array works here\n```\n\n```\narr.length <= 10^3\n```\n\nTried to approach this with sliding window, but struggled with coming up with non-brute force solution.

Had an interesting question today that I am still not sure how to approach:\n\nYou are given an array of positive/negative numbers that are not necessarily dist