Back to Freecodecamp

Problem 111: Primes with runs

curriculum/challenges/english/blocks/project-euler-problems-101-to-200/5900f3db1000cf542c50feee.md

latest1.8 KB
Original Source

--description--

Considering 4-digit primes containing repeated digits it is clear that they cannot all be the same: 1111 is divisible by 11, 2222 is divisible by 22, and so on. But there are nine 4-digit primes containing three ones:

$$1117, 1151, 1171, 1181, 1511, 1811, 2111, 4111, 8111$$

We shall say that $M(n, d)$ represents the maximum number of repeated digits for an n-digit prime where d is the repeated digit, $N(n, d)$ represents the number of such primes, and $S(n, d)$ represents the sum of these primes.

So $M(4, 1) = 3$ is the maximum number of repeated digits for a 4-digit prime where one is the repeated digit, there are $N(4, 1) = 9$ such primes, and the sum of these primes is $S(4, 1) = 22275$. It turns out that for d = 0, it is only possible to have $M(4, 0) = 2$ repeated digits, but there are $N(4, 0) = 13$ such cases.

In the same way we obtain the following results for 4-digit primes.

Digit, d$M(4, d)$$N(4, d)$$S(4, d)$
021367061
13922275
2312221
331246214
4328888
5315557
6316661
73957863
8318887
93748073

For d = 0 to 9, the sum of all $S(4, d)$ is 273700. Find the sum of all $S(10, d)$.

--hints--

primesWithRuns() should return 612407567715.

js
assert.strictEqual(primesWithRuns(), 612407567715);

--seed--

--seed-contents--

js
function primesWithRuns() {

  return true;
}

primesWithRuns();

--solutions--

js
// solution required