395. Count Commas in Range II

You are given an integer n. Return the total number of commas used when writing all integers from [1, n] (inclusive) in standard number formatting. In standard formatting: - A comma is inserted after every three digits from the right. - Numbers with fewer than 4 digits contain no commas. Note: because n can be as large as 10^15, both n and the answer are passed and returned as strings.