freeCodeCamp/curriculum/challenges/english/10-coding-interview-prep/project-euler/problem-413-one-child-numbers.md

id, title, challengeType, forumTopicId, dashedName

id	title	challengeType	forumTopicId	dashedName
5900f50a1000cf542c51001c	Problem 413: One-child Numbers	5	302082	problem-413-one-child-numbers

--description--

We say that a $d$-digit positive number (no leading zeros) is a one-child number if exactly one of its sub-strings is divisible by d.

For example, 5671 is a 4-digit one-child number. Among all its sub-strings 5, 6, 7, 1, 56, 67, 71, 567, 671 and 5671, only 56 is divisible by 4.

Similarly, 104 is a 3-digit one-child number because only 0 is divisible by 3. 1132451 is a 7-digit one-child number because only 245 is divisible by 7.

Let F(N) be the number of the one-child numbers less than N. We can verify that F(10) = 9, F({10}^3) = 389 and F({10}^7) = 277\\,674.

Find F({10}^{19}).

--hints--

oneChildNumbers() should return 3079418648040719.

assert.strictEqual(oneChildNumbers(), 3079418648040719);

--seed--

--seed-contents--

function oneChildNumbers() {

  return true;
}

oneChildNumbers();

--solutions--

// solution required