Yan Cui
I help clients go faster for less using serverless technologies.
This article is brought to you by
The real-time data platform that empowers developers to build innovative products faster and more reliably than ever before.
Problem
Some positive integers n have the property that the sum [ n + reverse(n) ] consists entirely of odd (decimal) digits. For instance, 36 + 63 = 99 and 409 + 904 = 1313. We will call such numbersreversible; so 36, 63, 409, and 904 are reversible. Leading zeroes are not allowed in either n or reverse(n).
There are 120 reversible numbers below one-thousand.
How many reversible numbers are there below one-billion (109)?
Solution
The solution I have posted here solves the problem but it takes a good 15 mins or so to run so doesn’t meet the 1 minute rule.. unfortunately brute force is the only way I know how to solve this problem :-(
Whenever you’re ready, here are 4 ways I can help you:
- Production-Ready Serverless: Join 20+ AWS Heroes & Community Builders and 1000+ other students in levelling up your serverless game. This is your one-stop shop for quickly levelling up your serverless skills.
- Do you want to know how to test serverless architectures with a fast dev & test loop? Check out my latest course, Testing Serverless Architectures and learn the smart way to test serverless.
- I help clients launch product ideas, improve their development processes and upskill their teams. If you’d like to work together, then let’s get in touch.
- Join my community on Discord, ask questions, and join the discussion on all things AWS and Serverless.