freeCodeCamp/curriculum/challenges/english/blocks/daily-coding-challenges-javascript/69373793f5a867f769cde137.md

id, title, challengeType, dashedName

id	title	challengeType	dashedName
69373793f5a867f769cde137	Challenge 152: Circular Prime	28	challenge-152

--description--

Given an integer, determine if it is a circular prime.

A circular prime is an integer where all rotations of its digits are themselves prime.

For example, 197 is a circular prime because all rotations of its digits: 197, 971, and 719, are prime numbers.

--hints--

isCircularPrime(197) should return true.

assert.isTrue(isCircularPrime(197));

isCircularPrime(23) should return false.

assert.isFalse(isCircularPrime(23));

isCircularPrime(13) should return true.

assert.isTrue(isCircularPrime(13));

isCircularPrime(89) should return false.

assert.isFalse(isCircularPrime(89));

isCircularPrime(1193) should return true.

assert.isTrue(isCircularPrime(1193));

--seed--

--seed-contents--

function isCircularPrime(n) {

  return n;
}

--solutions--

function isPrime(n) {
  if (n < 2) return false;
  for (let i = 2, sqrt = Math.floor(Math.sqrt(n)); i <= sqrt; i++) {
    if (n % i === 0) return false;
  }
  return true;
}

function rotations(num) {
  const str = num.toString();
  const result = [];
  for (let i = 0; i < str.length; i++) {
    result.push(str.slice(i) + str.slice(0, i));
  }
  return result.map(Number);
}

function isCircularPrime(num) {
  const rots = rotations(num);
  return rots.every(isPrime);
}