freeCodeCamp/curriculum/challenges/english/08-coding-interview-prep/project-euler/problem-52-permuted-multiples.english.md

id	challengeType	title
5900f3a01000cf542c50feb3	5	Problem 52: Permuted multiples

Description

It can be seen that the number, 125874, and its double, 251748, contain exactly the same digits, but in a different order. Find the smallest positive integer, x, such that 2x, 3x, 4x, 5x, and 6x, contain the same digits.

Instructions

Tests

tests:
  - text: <code>permutedMultiples()</code> should return 142857.
    testString: assert.strictEqual(permutedMultiples(), 142857, '<code>permutedMultiples()</code> should return 142857.');

Challenge Seed

function permutedMultiples() {
  // Good luck!
  return true;
}

permutedMultiples();

Solution

function permutedMultiples() {
    const isPermutation = (a, b) =>
        a.length !== b.length
            ? false
            : a.split('').sort().join() === b.split('').sort().join();


    let start = 1;
    let found = false;
    let result = 0;

    while (!found) {
        start *= 10;
        for (let i = start; i < start * 10 / 6; i++) {
            found = true;
            for (let j = 2; j <= 6; j++) {
                if (!isPermutation(i + '', j * i + '')) {
                    found = false;
                    break;
                }
            }
            if (found) {
                result = i;
                break;
            }
        }
    }

    return result;
}