Happy Number

EasyMathHashing

Solve this the way you would in the interview: out loud, on a timer, with an AI interviewer asking follow-ups while you code. You get a scored report at the end.

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Problem

Write an algorithm to determine if a number n is happy. A happy number is a number defined by the following process: - Starting with any positive integer, replace the number by the sum of the squares of its digits. - Repeat the process 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, and false if not.

Examples

Input: n = 19
Output: true
1^2 + 9^2 = 82 → 8^2 + 2^2 = 68 → 6^2 + 8^2 = 100 → 1^2 + 0 + 0 = 1.
Input: n = 2
Output: false

Constraints

  • 1 <= n <= 2^31 - 1

What the interviewer grades

A correct solution is one of five scores. The report also grades problem understanding (did you clarify inputs and edge cases before coding), problem solving, communication while you work, code quality, and testing. See a sample report, or read up on the pattern in the lessons.

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