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Archive for the ‘Advent Of Code’ Category

Advent Of Code: Day 8

09 Dec 2015
CTF: Advent Of Code
Link to challenge: http://adventofcode.com
Date Completed: 09 December 2015

Challenge

Solution

A fairly simple puzzle. My approach was to add up the strings together and use regular expressions to replace special characters with a * character so that the python len function would provide me with the correct result.

Script:

 

 
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Advent Of Code: Day 7

08 Dec 2015
CTF: Advent Of Code
Link to challenge: http://adventofcode.com
Date Completed: 07 December 2015

Challenge

Solution

Wow this one was fun! I decided to use Z3Py, a theorem prover module for python. My solution essentially parses each command using regexp and adds the various boolean rules to a solver object. Finally, the theorem solver checks all possible values and prints out the results of every ‘wire’. Determining the answer is then very simple. To solve part 2 I simply changed the value of b in my input.txt to the answer from part a and reran the script.

 

 
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Advent Of Code: Day 6

06 Dec 2015
CTF: Advent Of Code
Link to challenge: http://adventofcode.com
Date Completed: 06 December 2015

The Challenge

Solution

I split up the solutions for part 1 and part 2. Was almost tempted to go for a numpy and scipy sparse matrix solution but a 1000×1000 matrix is small enough for a dense matrix.

Part 1

 

Part 2

 

 
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Advent Of Code: Day 5

05 Dec 2015
CTF: Advent Of Code
Link to challenge: http://adventofcode.com
Date Completed: 05 December 2015

The Challenge

Solution

Another quick and simple Python solution!

 

 
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Advent Of Code: Day 4

04 Dec 2015
CTF: Advent Of Code
Link to challenge: http://adventofcode.com
Date Completed: 04 December 2015

The Challenge

Solution

Because speed was not an issue in this case, I simply used python again to solve the problem. The script is a little slow taking ~10 seconds to compute the answer in my case. A C/C++ solution would be orders of magnitude faster.

 

 
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Advent Of Code: Day 3

04 Dec 2015
CTF: Advent Of Code
Link to challenge: http://adventofcode.com
Date Completed: 03/12/2015

The Challenge

Solution

A rather interesting challenge. I wasn’t too happy with my solution but it works.
I split up parts 1 and parts 2 so the code can be read more easily.

Part 1 – Santa Solo Trip

 

Part 2 – Santa + Robo Santa

I didn’t like the use of the santasTurn boolean here too much but couldn’t think of a nicer way to complete the task (in the 15 minutes before I went to sleep!).

 
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Advent Of Code: Day 2

02 Dec 2015
CTF: Advent Of Code
Link to challenge: http://adventofcode.com
Date Completed: 02/12/2015

The Challenge

Solution

This challenge was very simple. I whipped up a short python script that solves it. The use of sorted to get the second smallest integer is not pretty but insignificant with such small numbers.

 

 
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Advent Of Code: Day 1

02 Dec 2015
CTF: Advent Of Code
Link to challenge: http://adventofcode.com
Date Completed: 01/12/2015

The Challenge

 

Solution

Before part 2 of the problem was revealed I decided to tackle the problem using the command line. I cam up with the following command:

We echo the input and remove the ) symbol which leaves only ( and we use wc to count the number of  ( symbols which tells us how many times we went to a higher floor. We then subtract his number from the number of times we went to a lower floor (using bash arithmetic) which gives us our answer.

Part 2 of the problem would be annoying to do on the command line so I decided to write a quick python script to solve it. The solution also solves the first part of the problem (lol).

 

 
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