#2729 - Check if The Number is Fascinating

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Problem Description

You are given an integer n that consists of exactly 3 digits.

We call the number n fascinating if, after the following modification, the resulting number contains all the digits from 1 to 9 exactly once and does not contain any 0's:

Concatenate n with the numbers 2 * n and 3 * n.

Return true if n is fascinating, or false otherwise.

Concatenating two numbers means joining them together. For example, the concatenation of 121 and 371 is 121371.

Solution

/**
 * @param {number} n
 * @return {boolean}
 */
var isFascinating = function(n) {
  const concatenated = `${n}${2 * n}${3 * n}`;
  const digitSet = new Set(concatenated);
  return concatenated.length === 9 && digitSet.size === 9 && !digitSet.has('0');
};