freeCodeCamp/curriculum/challenges/english/10-coding-interview-prep/project-euler/problem-340-crazy-function.md

id, title, challengeType, forumTopicId, dashedName

id	title	challengeType	forumTopicId	dashedName
5900f4c21000cf542c50ffd4	Problem 340: Crazy Function	5	301999	problem-340-crazy-function

--description--

For fixed integers a, b, c, define the crazy function F(n) as follows:

$$\begin{align} & F(n) = n - c \;\text{ for all } n > b \\ & F(n) = F(a + F(a + F(a + F(a + n)))) \;\text{ for all } n ≤ b. \end{align}$$

Also, define S(a, b, c) = \displaystyle\sum_{n = 0}^b F(n).

For example, if a = 50, b = 2000 and c = 40, then F(0) = 3240 and F(2000) = 2040. Also, S(50, 2000, 40) = 5\\,204\\,240.

Find the last 9 digits of S({21}^7, 7^{21}, {12}^7).

--hints--

crazyFunction() should return 291504964.

assert.strictEqual(crazyFunction(), 291504964);

--seed--

--seed-contents--

function crazyFunction() {

  return true;
}

crazyFunction();

--solutions--

// solution required