← DSA Foundations
easyBasic Math Concepts

Count Digits

Count the decimal digits in a nonnegative integer. Zero has one digit.

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Work through the cases

3 examples

Input notation

An integer from 0 through 1000000000.

Expected result

The digit count.
Case 1

Input

4072

Expected output

4
Case 2

Input

0

Expected output

1
Case 3

Input

1000000000

Expected output

10

These notes use simplified input/output notation. The linked platform defines the method signature and judge format.

FROM IDEA TO IMPLEMENTATION

Understand the approach.

Compare the documented approaches below. Brute force, better, and optimal versions appear where available; a direct exercise may need only one approach.

Divide by 10 repeatedly. Handle zero as one digit. Time: O(d), where d is the digit count. Extra space: O(1).

import java.util.*;
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        ArrayList<Long> values = new ArrayList<>();
        while (in.hasNextLong()) values.add(in.nextLong());
        long[] a = values.stream().mapToLong(Long::longValue).toArray();
        long n = a[0];
        int count = 1; while (n >= 10) { n /= 10; count++; } System.out.println(count);
    }
}

Reference code. Platform solutions may use supplied node types, imports, or collection libraries; foundational examples are complete programs.