3883. Count Non Decreasing Arrays With Given Digit Sums

You are given an integer array digitSum of length n. An array arr of length n is considered valid if: - 0 <= arr[i] <= 5000 - it is non-decreasing. - the sum of the digits of arr[i] equals digitSum[i]. Return an integer denoting the number of distinct valid arrays. Since the answer may be large, return it modulo 109 + 7. An array is said to be non-decreasing if each element is greater than o