You are given an integer n and a 2D array requirements, where requirements[i] = [endi, cnti] represents the end index and the inversion count of each requirement. A pair of indices (i, j) from an integer array nums is called an inversion if: Return the number of permutations perm of [0, 1, 2, ..., n - 1] such that for all requirements[i], perm[0..endi] has exactly cnti inversions. Since the answer may be very large, return it modulo 109 + 7.