Advent of Code 2020

Me, trying to solve a few puzzles in Haskell

Running the Code

We use day 1 as an example here, this can be used for each day:

• runghc Day.hs to run the code
• runghc Day-test.hs to run the tests

To do it interactively, start ghci, then run:

• :l Day1-test.hs and runTestTT tests to run the tests
• :l Day1.hs and Day1.main to run the code

I'm also using hlint to check for suggestions.

Day 1

Given a text file (Day1.txt) that contains an integer in each line:

• Task 1: Find a pair of numbers that adds up to 2020, the result is their product
• Task 2: Find a triple of numbers that adds up to 2020, the result is their product

Day 2

Given a text file (Day2.txt) that contains a list of password policies and passwords that look like this:

1-3 a: abcde

Where 1 is the first number, 3 is the second number, a is the character and abcde is the password. The task is to find the amount of passwords that are valid according to the policy. The policy is different between the two tasks:

• Task 1: There are between first number and second number of character in the password (in the example above, that would be at least 1 and at most 3 as in abcde.
• Task 2: There is either character at the position described by the first number or the second number (but not both), where position is 1-indexed.