Count how many comma characters appear when writing every integer in an inclusive range with standard thousands separators.
Count Commas in Range
You are given two integers l and r with l <= r. Consider writing every integer from l to r inclusive using standard decimal formatting with commas as thousands separators.
For example:
1000is written as1,0001234567is written as1,234,567999has no comma
Your task is to compute the total number of comma characters that appear across all numbers in the range.
Return the total count.
Notes
- Only commas in the usual thousands-separator positions are counted.
- No commas are inserted for numbers below
1000. - The range is inclusive.
Input Format
- The first line contains two integers
landr. l <= r.
Output Format
- Return a single integer: the total number of comma characters used when formatting all integers in
[l, r]inclusive.
Constraints
0 <= l <= r- The answer fits in a 64-bit signed integer.
- The range may be large enough that iterating over every number is not intended.
Example 1
Input
l = 1, r = 20
Output
0
Explanation
All numbers from 1 to 20 have fewer than 1000, so none contain commas.
Example 2
Input
l = 998, r = 1002
Output
3
Explanation
998 and 999 have 0 commas. 1000, 1001, and 1002 each have 1 comma. Total = 3.
Show 1 more example
Example 3
Input
l = 1000, r = 2005
Output
1006
Explanation
Every number from 1000 to 2005 contains exactly one comma, and there are 1006 such numbers.
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