Follow the Rabbit

Find secrets phrases corresponding to anagrams of poultry outwits ants with definied MD5 hash.

This program solves the Code Challenge provided by trustpilot.

Getting Started

Concept

The main idea is to construct a trie of letters and check each time if character can be consumed. If not, then no need to test the next characters.

Example:

<> : last character of a word

            ''
         /      \     \
       /         \     \
     't'         'w'    'y'
      |           |      |
     'r'         'a'    'o'
      |           |      |
     'u'         'n'   <'u'>
    /    \        |
   's'   't'    <'t'>
    |      |      |
  <'t'>  <'h'>  <'s'>
  /   \
 'p'  'i'
  |    |
 'i'  'n'
  |    |
 'l' <'g'>
  |
 'o'
  |
<'t'>

Build

As for now, to build the project you need nightly Rust.

cargo build

Or with rustup:

rustup run nightly cargo build

It is encouraged to use the option --release for better performance.

Visual Studio Code

Tasks are configured to run with rustup. It is also possible to debug the project thanks to LLDB Debugger.

Usage

Once the project compiled, you can find the binary either on ./target/release/follow-rabbit or ./target/debug/follow-rabbit depending on the chosen profile.

$ follow-rabbit --help
Follow the Rabbit and see how deep the hole goes. 1.0.0
yowari <yowari@outlook.com>
Search for anagrams

USAGE:
    follow-rabbit [OPTIONS]

FLAGS:
    -h, --help       Prints help information
    -V, --version    Prints version information

OPTIONS:
    -d, --dictionary <FILE>    Select the dictionary file. Default = wordlist
    -w, --words <INTEGER>      Set the maximum number of words in an angram. Default = 4
    -l, --length <INTEGER>     Set the minimum length of a word. Default = 2
    -o, --output <FILE>        Output file path. Default = anagrams

Results

Of course I will not give you the secrets phrases. Find it yourself 😛. But I can share some benches.

During the benches, the release build was used. RAM consumption was about 3 Mo. Thanks to Rust not having VM or garbage collector 😎

1. The easiest secret phrase

$ follow-rabbit --words=3 --length=5

Execution time was about 3 secs.

2. The more difficult secret phrase

$ follow-rabbit --words=3 --length=2

Execution time was about 1 minute.

3. The hard secret phrase

$ follow-rabbit --words=4 --length=2

Execution time was about 1 hour.