2023-12-10.md

Computers & Data

Agenda

1. What are Computers?
   • Computers vs Calculators
     • Computers are programmable
     • Computers can run new algorithms
   • Transistors, Binary, Logic
     • The fundamental things a computer can do is very limited, it just does it very quickly to make up for it.
     • Analysing how we using our base-10 numbers, we can apply the same method to only two states. On-or-off, Yes-or-no, Electricity-or-no-electricity to represent arbitrarily large numbers.
     • Lots of operations derive from very simple building blocks
     • Other data (like text) can be sent as blocks of binary representing the parts that it is made of:
       • Images: Pixels are blocks of colour values
       • Text: Sequence of numbers we assigned to represent characters
2. What is an Algorithm?
   • A finite sequence of steps
3. Advent of Code 2023, Day 1, Part 1 Pair-programming
   • (Optional) Set up VSCode on Izabela's machine for live-share
   • (Optional) Using Izabela's puzzle input

Advent of Code

We logged in with GitHub and solved Day 1 Part 1 together in Pair-programming. Markus doing the python, Izabela bringing the solution / algorithm ideas.

Day 1, Part 1

• Advent of Code: Calendar
• Advent of Code: Day 1 "Trebuchet!?"

Steps

1. Define goal: What should the algorithm do
2. Get it to work on a single example
3. Change the example to test if it still works
4. Change it to run on the actual puzzle input
5. See if the result is correct
   • if not: start debugging!

we ended up with this code, and a correct result on the first try.

# Advent of Code, Day 1

## Algorithm
# 1. What should it do?
#   0. read all the input
#   - figure out first and last number in a line
#      - HOW?
#   - put them together: "1" and "2" turns into "12"
#      - "tre7buchet"[3] == "7"
#      - HOW?
#   - afterwards add them all together
#      - HOW?


puzzleFile = open("Puzzle")
lines = puzzleFile.readlines()
totalOfNumbers = 0

lineNumber = 0
while (lineNumber < len(lines)):
    text = lines[lineNumber]
    lineNumber = lineNumber + 1

    firstDigitWeFound = "not found"
    lastDigitWeFound = "not found"

    counter = 0
    while (firstDigitWeFound == "not found"):
        character = text[counter]
        counter = counter + 1

        if character.isdigit(): # if it looks like a number
            firstDigitWeFound = character # it's the first one we found!

    counter = len(text) - 1
    while(counter >= 0 and lastDigitWeFound == "not found"):
        character = text[counter]
        counter = counter - 1
        if character.isdigit():
            lastDigitWeFound = character

    found = f"{firstDigitWeFound}{lastDigitWeFound}"
    foundNum = int(found) # "12" -> 12

    print(f"in {text} we found {found}")
    totalOfNumbers = totalOfNumbers + foundNum
    print(f"our total so far is: {totalOfNumbers}")

print(f"the final total is: {totalOfNumbers}")

TODO

• Izabela: Look at Day 1 Part 2 and how it differs from Day 1 Part 1. Why is it harder?
• Markus: Figure out how Izabela can stay active learning Python during XMAS break.