[2015-11-02] Challenge #239 [Easy] A Game of Threes : dailyprogrammer

[2015-11-02] Challenge #239 [Easy] A Game of Threes : dailyprogrammer

Back in middle school, I had a peculiar way of dealing with super boring classes. I would take my handy pocket calculator and play a "Game of Threes". Here's how you play it:

First, you mash in a random large number to start with. Then, repeatedly do the following:

• If the number is divisible by 3, divide it by 3.
• If it's not, either add 1 or subtract 1 (to make it divisible by 3), then divide it by 3.

The game stops when you reach "1".

While the game was originally a race against myself in order to hone quick math reflexes, it also poses an opportunity for some interesting programming challenges. Today, the challenge is to create a program that "plays" the Game of Threes.

Challenge Description

The input is a single number: the number at which the game starts. Write a program that plays the Threes game, and outputs a valid sequence of steps you need to take to get to 1. Each step should be output as the number you start at, followed by either -1 or 1 (if you are adding/subtracting 1 before dividing), or 0 (if you are just dividing). The last line should simply be 1.

Input Description

The input is a single number: the number at which the game starts.

100  

Output Description

The output is a list of valid steps that must be taken to play the game. Each step is represented by the number you start at, followed by either -1 or 1 (if you are adding/subtracting 1 before dividing), or 0 (if you are just dividing). The last line should simply be 1.

100 -1  33 0  11 1  4 -1  1  

Challenge Input

31337357  

Fluff

Hi everyone! I am /u/Blackshell, one of the new moderators for this sub. I am very happy to meet everyone and contribute to the community (and to give /u/jnazario a little bit of a break). If you have any feedback for me, I would be happy to hear it. Lastly, as always, remember if you would like to propose a challenge to be posted, head over to /r/dailyprogrammer_ideas.

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