freeCodeCamp/problem-277-a-modified-collatz-sequence.english.md at 1f310d8c5877a13cf67fbfaad323b4a558a0ac3c

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Valeriy 79d9012432 fix(curriculum): quotes in tests (#18828 )

* fix(curriculum): tests quotes

* fix(curriculum): fill seed-teardown

* fix(curriculum): fix tests and remove unneeded seed-teardown

2018-10-20 23:32:47 +05:30

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id, challengeType, title

id	challengeType	title
5900f4811000cf542c50ff94	5	Problem 277: A Modified Collatz sequence

Description

A modified Collatz sequence of integers is obtained from a starting value a1 in the following way:

an+1 = an/3 if an is divisible by 3. We shall denote this as a large downward step, "D".

an+1 = (4an + 2)/3 if an divided by 3 gives a remainder of 1. We shall denote this as an upward step, "U".

an+1 = (2an - 1)/3 if an divided by 3 gives a remainder of 2. We shall denote this as a small downward step, "d".

The sequence terminates when some an = 1.

Given any integer, we can list out the sequence of steps. For instance if a1=231, then the sequence {an}={231,77,51,17,11,7,10,14,9,3,1} corresponds to the steps "DdDddUUdDD".

Of course, there are other sequences that begin with that same sequence "DdDddUUdDD....". For instance, if a1=1004064, then the sequence is DdDddUUdDDDdUDUUUdDdUUDDDUdDD. In fact, 1004064 is the smallest possible a1 > 106 that begins with the sequence DdDddUUdDD.

What is the smallest a1 > 1015 that begins with the sequence "UDDDUdddDDUDDddDdDddDDUDDdUUDd"?

Instructions

Tests

tests:
  - text: <code>euler277()</code> should return 1125977393124310.
    testString: assert.strictEqual(euler277(), 1125977393124310, '<code>euler277()</code> should return 1125977393124310.');

Challenge Seed

function euler277() {
  // Good luck!
  return true;
}

euler277();

Solution

// solution required

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