LeetCode Entry

3870. Count Commas in Range

08.09.2026 easy 2026 kotlin rust

Count commas in numbers range

3870. Count Commas in Range easy substack youtube

https://dmitrysamoylenko.com/leetcode/

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Problem TLDR

Count commas in numbers range

Intuition

Brute-force is accepted, each number to string and length/3. Clever way is to spot at most one comma under 10^5 range.

Approach

• only the first 999 doesnt have it

Complexity

• Time complexity: \(O(1)\)

• Space complexity: \(O(1)\)

Code

    fun countCommas(n: Int)=max(0,n-999)

    pub fn count_commas(n: i32) -> i32 { 0.max(n-999) }