Count Commas in Range - Solution & Explanation

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.

 

Example 1:

Example 2:

 

Constraints:

• 1 <= n <= 105