Hello, today, we gonna discuss the count digit problem. Let’s start.

If you prefer watching over reading, don't worry! You can also check out my detailed video:

What is the count digit problem?

🤔I think we don’t need to explain so much math stuff, I will just show you some examples and you will be able to understand some patterns.

Pattern

Little Quiz

But, you told me, I know how to count, but how to explain it to my computer?

Problem Statement

Given a number N, the task is to return the count of digits in this number.

The main idea is to remove digits one by one and take a count

How to remove the digits?

If you’d like to remove a digit, you should divide our number by 10. For example: If we divide 255 by 10 it gives us 25. We will remove the last digit.

How long do we remove digits?

Let’s divide our number 255 by 10 till some point.

• 255 divided by 10, which gives us 25.

• 25 divided by 10, the result is 2.

• 2 divided by 10, gives us 0.

And our 0 is some point when we should stop to divide our number by 10.

Take a pause and try it

Please have a little break and did it:

Explaining of Code

Let's take number = 123:

• In the first iteration, we divide 123 by 10, which gives us 12

• In the second iteration, we divide 12 by 10, resulting in 1.

• In the third iteration, we divide 1 by 10, which gives 0.

Our time complexity will be Theta(d) - where d is the number of digits in the number.

Conclusion

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