Advent of Code, 2024 - Day 01

Hi,

there is a nice algorithmic challenge each year, called Advent of Code.

Link for this year is:
https://adventofcode.com/2024

I attach my naive solutions, we can think if and how they can be improved, if you want.

SPOILERS BELOW

Link to the task assignment: https://adventofcode.com/2024/day/1

Please make sure you download your input.txt file from the page above and that you pass it as parameter to the scripts below (for example in thinAir, you enter input.txt to Script/Command line... if you stored the file side by side with the solutions)

Part 1

The assignment says "Pair up the smallest number in the left list with the smallest number in the right list, then the second-smallest left number with the second-smallest right number, and so on.". You than need to create sum of these differences - a distance score.

Code:

---

uses "console", "file"


function tbmain()
  string inputFile = app.ArgV(2)
 
  if not file_exists(inputFile) then
    printl inputFile
    printl "Please specify valid input file as first parameter of the script"
    waitkey
    return 1
  end if
 
  string inputContent = file_load(inputFile)

  string lines()
  long entryCount = parse(inputContent, lines, $LF) - 1 ' Last line left empty

  ' First, let's load each column individually
  long leftList(entryCount)
  long rightList(entryCount)

  long columns(2)
  for i as long = 1 to entryCount
    split(lines(i), "  ", columns)
    leftList(i)  = columns(1)
    rightList(i) = columns(2)
  next

  ' ...for easy individual sort
  array sort leftList(), ascend
  array sort rightList(), ascend

  ' ...to calculate distance score
  long distance
  for i as long = 1 to entryCount
    distance += abs(rightList(i) - leftList(i))
  next

  printl distance, "is the distance" in 14

  waitkey
end function

---

Part 2
In the second part, the tasks changes to a different one: "You'll need to figure out exactly how often each number from the left list appears in the right list. Calculate a total similarity score by adding up each number in the left list after multiplying it by the number of times that number appears in the right list."

Code:

---

uses "console", "file"


function tbmain()
  string inputFile = app.ArgV(2)
 
  if not file_exists(inputFile) then
    printl inputFile
    printl "Please specify valid input file as first parameter of the script"
    waitkey
    return 1
  end if
 
  ' In theory, I would not need to load whole file to memory in this exercise, but it is small
  string inputContent = file_load(inputFile)

  string lines()
  long entryCount = parse(inputContent, lines, $LF) - 1 ' Last line left empty

  ' I will store key-value pairs of number & its occurence count for each column
  dword totalColumnNumberCounts(2)  = hash_new(entryCount), hash_new(entryCount)
  long rowValue(2)
 
  ' Let's find number of value occurences in each column
  long idOccurrence(2)
  for i as long = 1 to entryCount
    split(lines(i), "  ", rowValue)
 
    IncreaseHashValue(totalColumnNumberCounts(1), rowValue(1), 1)
    IncreaseHashValue(totalColumnNumberCounts(2), rowValue(2), 1)
  next

  ' First, we need to find unique keys in the left column
  string idsCommaSeparated = Hash_GetKeys(totalColumnNumberCounts(1), ",")
  string id()
  parse(idsCommaSeparated, id, ",")
 
  long similarity
 
  ' Second, we calculate the similarity score
  for i as long = 1 to countof(id)
    idOccurrence(1) = hash_get(totalColumnNumberCounts(1), id(i))
    idOccurrence(2) = hash_get(totalColumnNumberCounts(2), id(i))
   
    similarity += val(id(i)) * idOccurrence(1) * idOccurrence(2)
  next
 
  hash_free(totalColumnNumberCounts(1))
  hash_free(totalColumnNumberCounts(2))

  printl similarity, "is the similarity score" in 14

  waitkey
end function

function IncreaseHashValue(hashHandle as dword, hashValue as long, amount as long)
  long currentCount = val(hash_get(hashHandle, hashValue)) + amount

  hash_set(hashHandle, hashValue, currentCount)
end function

---