You are given an integer n and a list ranges where each ranges[i] = [l, r] means the sum of the values at positions l through r, 1-indexed and inclusive, of an unknown array of n integers is known. The actual sums are not given, only which ranges are known.
A position is recoverable if its value is the same in every array of n integers that is consistent with the known ranges.
Return the recoverable positions in increasing order. Return an empty array if none are recoverable.
Note that ranges may contain duplicate entries.
Input: n = 3, ranges = [[1,3],[1,2]]
Output: [3]
Explanation: The sum from 1 to 3 and the sum from 1 to 2 are both known, so their difference fixes position 3 no matter what the two sums actually equal.
Input: n = 5, ranges = [[1,2],[4,5]]
Output: []
Explanation: The two known sums do not overlap or share an endpoint, so no single position is forced to one value.
ranges.length ≤105[l, r] in ranges