# AOC 2022: Solution for Day 5

My solution for advent-of-code day 5

Advent of Code challenge #5 is all done, and I’m officially caught up!

The “hard-part” of this challenge for me was the just making the data usable. The actual task of moving the things around based on steps was pretty quick to implement. These are my-least favorite kind of advent of code challenges because it feels a bit like artificial difficulty in video games.

The functionality that “solved” the challenge was 31 loc, but the ingest functionality took 33 loc. Half the work was just getting the information I needed into a usable data structure. why not just provide things in a useable format from the jump? Maybe I’m missing the point and the ingest is supposed to be a fun part of the challenge and just doesn’t vibe with me.

/rant.

Anyways, here’s my solution for part 1 and part 2 of day 5’s challenge:

"""

steps for part 1 of today's challenge:
1. load in the cargo stacks as input
2. load in the steps that you need to take on input
3. follow the steps in step 2 on the stacks
4. grab the top items from each stack
"""

from typing import List
from functools import reduce

"""loads the cargo stacks from the input.txt file"""
with open('input.txt', mode='r', encoding='utf-8') as file:
lines = [line.strip('\n') for line in file.readlines()]

# get number of stacks in the cargo
last_line = lines[len(lines)-1].replace(' ', '')
num_stacks = range(int(last_line[len(last_line)-1]))

# create cargo stacks
stacks = [[] for stack in num_stacks]
for line in lines[:-1]:
curr_pos = 0
for idx, stack in enumerate(num_stacks):
curr_char = line[curr_pos:curr_pos+3]
curr_pos += 4
if curr_char.replace(' ', '') != "":
stacks[idx].append(curr_char)
return stacks

"""load the steps and format them from steps.txt"""
with open('steps.txt', mode='r', encoding='utf-8') as file:
lines = [line.strip('\n') for line in file.readlines()]
steps = []
for line in lines:
tokens = line.split(' ')
steps.append({
"num": int(tokens[1]),
"from": int(tokens[3]),
"to": int(tokens[5])
})
return steps

def move_cargo(cargo: List[List], steps: List[dict]):
"""move cargo from one position to another one by one.
"""
for step in steps:
to_move = step.get('num')
idx_from = step.get('from') - 1
idx_to = step.get('to') - 1

# grab items from cargo[idx_from]
items_moving = [cargo[idx_from].pop(0) for x in range(to_move)]

# move items into cargo[idx_to]
for item in items_moving:
cargo[idx_to].insert(0, item)
return cargo

def move_cargo_groups(cargo: List[List], steps: List[dict]):
"""move cargo from one position to another while holding the original shape.
"""
for step in steps:
to_move = step.get('num')
idx_from = step.get('from') - 1
idx_to = step.get('to') - 1

# grab items from cargo[idx_from]
items_moving = cargo[idx_from][0:to_move]
cargo[idx_from] = cargo[idx_from][to_move:]

# move items into cargo[idx_to]
cargo[idx_to] = items_moving + cargo[idx_to]
return cargo

if __name__ == "__main__":

# part 1: move cargo conventionally
new_cargo = move_cargo(cargo, steps)
top_cargo = reduce(lambda a, c: a + c[0], new_cargo, '')

print(top_cargo.replace('[', '').replace(']', ''))

# part 2: margo cargo in groups

group_cargo = move_cargo_groups(cargo, steps)
top_group_cargo = reduce(
lambda a, c: a + c[0] if len(c) > 0 else a, group_cargo, '')

print(top_group_cargo.replace('[', '').replace(']', ''))