Google Code-in

Objective

Improve Julia coding skills.

Introduction

Bitcoin is going crazy these days and mining a new coin is becoming more and more difficult. Why chase after the hot stuff? We have something easier here!

Introducing the Julian Coin - it's easy to mine and it's based upon a common hashing algorithm called MD5. Each coin can be discovered from a secret. To start mining, concatenate the secret with a positive integer and run it through the MD5 hashing algorithm. You get the coin by finding the smallest number that gives you a hash code both starting and ending with 3 zeros. (You may use any MD5 library.)

For examples:

• Secret hello requires 6144434 to get the coin
• Secret julia requires 1436069 to get the coin

We can prove it from a Unix terminal:

$ echo -n "hello6144434" | md5sum
0006a1061ece946b7e95c2af73773000

$ echo -n "julia1436069" | md5sum
000d02cb0a523a25820ea72bb959d000

What to do

Write a function mine_julian_coin(s::String) that returns the number and the corresponding hash code as a named tuple.

For example:

julia> mine_julian_coin("hello")
   (key = 6144434, hash = "0006a1061ece946b7e95c2af73773000")

Can you use your program to mine the Julian Coin with secret super awesome?

How to submit your solution?

You can publish your code on GitHub in a repository or as a public gist. Include the link in the comments.