Taken from DailyCodingProblem

A number is considered perfect if its digits sum to exactly 10.

Given a positive integer n, return the n-th perfect number.

For exmaple, given 1, you should return 19. Given 2, you should return 28.

Solution

This is the answer I came up with:

function perfect(n: number): number {
  let digits = [n, 0]
  while (digits[0] + digits[1] !== 10) {
    digits[1]++
  }
  return Number(digits.join(''))
}

Testing

Solution tested in REPL:

https://www.typescriptlang.org/play?#code/GYVwdgxgLglg9mABABwKYCdiugCjALkTBAFsAjDASkOPI0QG8AoRRAG1SkQBMYBzGFADOiALyIA2mAA0iAAwBdFogDuACxgdEOXgOETFiANQ9+goRICMCxAEJR4y3MqNlrXeasKjR5QF9ldE4QdCQAOVIKdB0zYQA6ACs4GDAcAHI0ykomAKYIBCE4Dji2OD4cZTRMbCgcS0pZAHpGxEsATkqMLFwAJgbEZsQegA5O6twAVhdBiYmmSiA