Section 1Understand Problem
Section 01
Understand the problem
Restate the problem precisely. Interviewers reward candidates who pause, define the contract, and name the guarantees before coding.
Problem statement
Write an algorithm to determine if a number `n` is happy. A happy number is defined by the following process: starting with any positive integer, replace the number by the sum of the squares of its digits; repeat until the number equals 1 (where it will stay), or it loops endlessly in a cycle which does not include 1. Those numbers for which this process ends in 1 are happy. Return `true` if `n` is a happy number, `false` if not.
Example
n = 19 → true
Constraints
1 ≤ n ≤ 2³¹ − 1
Audio recording unsupported on this browser.
WPM—Fillers0Pace—Thinking0%
Explain the problem in your own words
0 words0 chars
AI Review
Write your thinking above first.
Once you've drafted a response, click Submit for AI review and a senior engineer will critique your reasoning.
Ready to submit Section 1?
The reviewer will check whether you stated inputs, output, guarantees, and any assumption you flagged.
Write at least a couple of sentences explaining the problem before submitting.