Advent of Code 2022

Day 03

zip

• combine multiple lists
• it is also possible to unzip

# key: value
dict(zip(list1, list2))

# set of tuples
set(zip(list1, list2))

# list of tuples
list(zip(list1, list2))

# iteration with count/index
for i, (name, age) in enumerate(zip(names, ages)):
    print(i, name, age)
    # 0 Jesus 33

# iteration
for (name, age) in zip(names, ages)):
    print(name, age)
    # Jesus 33

divide

5 / 2  # 2.5
5 // 2 # 2

islice

Read multiple lines at a time

from itertools import islice

with open('input.txt') as file:
   while True:
       group_lines = list(islice(file, 3))  # 3 lines at a time
       if not group_lines:
           break

intersection

intersection of 2 sets

result = set1 & set2

intersection of 3 sets

result = set1.intersection(set2, set3)

Day 05

readlines(): put all the lines of a file in a list

lines = file.readlines()
crates = lines[:8]
moves = lines[10:]

reverse a list

• reverse the current list: my_list.reverse()
• reverse for iteration: for elem in reversed(my_list)

Day 06

Create an empty set

my_set = set()
my_list = []
my_dict = {}

Day 07

PurePath(): path that might not exist on a filesystem

• useful to call path functions such as:
  • parent
  • parents
  • basename
  • extension
  • longer_path = path / new_dir
• sorted a list
  • result = sorted(list)[0]

Day 08

Part 1

why not 2d list

• can't make slices vertically

why not matrix

• matrix is a subclass of ndarray
• don't need matrix for [m,n] access of elements

why not np.ndarray

• np.array is the preferred method to create an ndarray
• np.array
• np.empty
• np.zeros

logging warning

• do not use fstring, use %s formatting to use optimization in logging library

Day09

Part 1

problem initiating list of tuples, hashing error

visited = [tuple([0,0])]

Part 2

skip: need to find/guess what the correct algorithm