3870. Count Commas in Range

Description

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:

Example 1:

Input: n = 1002

Output: 3

Explanation:

The numbers "1,000", "1,001", and "1,002" each contain one comma, giving a total of 3.

Example 2:

Input: n = 998

Output: 0

Explanation:

All numbers from 1 to 998 have fewer than four digits. Therefore, no commas are used.

Constraints:

Numbers from 1 to 999 contain no commas, so when $n$ is less than or equal to 999, the answer is 0.

Since the range of $n$ is $[1, 10^5]$, when $n$ is greater than or equal to 1000, each number contains exactly one comma, so the answer is $n - 999$.

Therefore, the answer is $\max(0, n - 999)$.

The time complexity is $O(1)$, and the space complexity is $O(1)$.

class Solution {
    public int countCommas(int n) {
        return Math.max(0, n - 999);
    }
}

class Solution {
public:
    int countCommas(int n) {
        return max(0, n - 999);
    }
};

class Solution:
    def countCommas(self, n: int) -> int:
        return max(0, n - 999)

func countCommas(n int) int {
	return max(0, n-999)
}

function countCommas(n: number): number {
    return Math.max(0, n - 999);
}