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Saturday 2024-12-07 – Link List

Blogging Intensifies Link List for Saturday 2024-12-07

Advent of Code 2024 – Day 06 – Guard Gallivant

It’s happening already. The slow crushing creep of laziness. I have not done part 2, yet, and I will, maybe get to it. I have ideas for how to solve part 2, its just… Kind of tedious and I want a respite.

Part 1 was fun though. Basically just, a simple pathfinding robot to trace the path of a guard through a maze of obstacles. I even gave it the ability to draw the map, but the dataset is bigger than my monitor so the refresh and drawing it’s stupid ugly with the real data set. I also turned it off because it drags the entire process to a crawl. A seconds-long calculation takes minutes and counting when its drawing nonsense.

The sample dataset looks neat though when drawn.

Part 2 is to find every place you could drop an object to create a loop for the guard. I thought I had it, I had the right idea, but I only ended up finding all of the existing loops. And I am not sure some were not in the middle of “walls”.

I got to thinking about what I did wrong, which is basically, checking for squares (loops) instead of finding them. I got to thinking about new algorithms to check all directions instead of just one, but what I need to do is to check along each side for walls and see if the gap is longer than the previous sides.  But that’s not going to work exactly, so I think I can use the distances traveled to see if there are places to drop objects based on if sides are shorter than the previous sides.

That probably made more sense in my head.

It probably isn’t that hard, I just, don’t feel like doing it right now. Occasionally there is a stupid simple one thrown in that takes 5 minutes to do both parts, maybe I can come back to today on that day.

Or maybe just sometime tomorrow, tomorrow is surprisingly pretty open.

Anyway, here is the code, I trimmed out the useless part 2 function.

import time
import os

with open("Day06Input.txt") as file:
    data = file.read()

lines = data.split("\n")
lines.pop()

guard = [0,0,0]
grid = []
guard_active = True
total = 0
total2 = 0
distances = []
cur_steps = 0

for each in lines:
  if "^" in each:
    guard[0] = each.index("^")
    guard[1] = lines.index(each)
#  print(guard)
  grid.append(list(each))

def print_grid(thegrid):
  for each in thegrid:
    print("".join(each))

#print_grid(grid)

def move_guard(thegrid, guard_pos):
# 0 - North, 1 - East, 2 - South, 3 - West
# Defind in guard[2]
# guard[0] = x coord (across rows), guard [1] = y coord (up and down lines)
  step = 1
  if (thegrid[guard_pos[1]-1][guard_pos[0]] != "#") and guard_pos[2] == 0:
    thegrid[guard_pos[1]][guard_pos[0]] = "X"
    thegrid[guard_pos[1]-1][guard_pos[0]] = "^"
    guard_pos[1] = guard_pos[1]-1
  elif (thegrid[guard_pos[1]][guard_pos[0]+1] != "#") and guard_pos[2] == 1:
    thegrid[guard_pos[1]][guard_pos[0]] = "X"
    thegrid[guard_pos[1]][guard_pos[0]+1] = "^"
    guard_pos[0] = guard_pos[0]+1
  elif (thegrid[guard_pos[1]+1][guard_pos[0]] != "#") and guard_pos[2] == 2:
    thegrid[guard_pos[1]][guard_pos[0]] = "X"
    thegrid[guard_pos[1]+1][guard_pos[0]] = "^"
    guard_pos[1] = guard_pos[1]+1
  elif (thegrid[guard_pos[1]][guard_pos[0]-1] != "#") and guard_pos[2] == 3:
    thegrid[guard_pos[1]][guard_pos[0]] = "X"
    thegrid[guard_pos[1]][guard_pos[0]-1] = "^"
    guard_pos[0] = guard_pos[0]-1
  else:
    guard_pos[2] = (guard_pos[2]+1) % 4
    step = 0
#  print(guard_pos)

  return thegrid, guard_pos, step


while guard_active:
  this_step = 0
  grid, guard, this_step = move_guard(grid, guard)
  if this_step == 0:
    distances.append(cur_steps)
    cur_steps = 0
  else:
    cur_steps += this_step
# Optionally Print the Map
#  print_grid(grid)
#  time.sleep(.001)
#  os.system('clear')
#  print(guard)
#  print(len(grid)-1)
  if guard[1] >= len(grid)-1 or guard[1] <= 0 or guard[0] >= len(grid[0])-1 or guard[0] <= 0:
    grid[guard[1]][guard[0]] = "X"
    guard_active = False
    print("The guard has left the area!")

for each in grid:
  total+= each.count("X")

#Print the final grid for fun
#print_grid(grid)

print(distances)

print(total)
# 5318
print(total2)

Advent of Code 2024 – Day 05 – Print Queue

Well, it’s an easy and hard-ish day.  I kind of hate the part 2s on these because they are almost always annoying.  It was a bit more interesting on the input because it was a two part input.  I’m still getting weird empty spaces at the end too, which I have just been trimming with a .pop(), but that’s a bit sloppy.  Today’s puzzle is verifying sorting of sets of numbers.

Part 1 was pretty simple, mostly because I forced myself not to “overthink it”.  I just, compared every pair set to the valid list.  Then if they were valid, added them into the total.  It feels like it’s going to miss some things, but it didn’t.  I got the correct answer in one try.

Part 2 was a pain.  It was, “take the wrong answers and fix them”.  What I did initially was just, swap the numbers if they were wrong.  This would put them one step closer to correct, afterwards, it fed them back through the check, this time flagged as bad, since the two sets need to be answered separately.  This code worked for the sample input for both parts. 

When I ran it through my actual data, this resulted in an answer of “5692”, which was incorrect.  Everything seemed correct in the code.  I even created a copy of the sorting loop with a “total3”, this time just running through bad pages.  It matched the answer of 5692.  So I started trying to guess a bit to see if I was even close I was within 100 for sure.  I went off to Reddit and pulled someone else’s code, ran my data set through it, and got the answer “5770”, which is the correct answer.

It also gave me a direction on where to look.  I tried a different sort where I just, slapped the first number at the end and sorted it back through.  It returned the same 5692.  Which would be a good sign, that both sorts were getting the same results, if the answer was correct.  On a bit of a lark, I decided to see just how off I was, 5770-5692 is 78.  In the data, on the last line, is a 78.  This was the key to solving the problem.  I uncommented some of my print statements and, sure enough, it wasn’t running the last line.

You know that .pop() I mentioned back at the start of this?  Well, it turns out that the sample data had an extra blank.  My actual data, did not, so it was just, dropping the last line of data.

Remember when I said it was a bad idea?

with open("Day05Input.txt") as file:
    data = file.read()


rules = data.split("\n\n")[0].split("\n")
pages = data.split("\n\n")[1].split("\n")
#pages.pop()
bad_pages = []

#Verify Inputs
#for each in pages:
#for each in rules:
#  print(each)

total = 0
total2 = 0
total3 = 0

for each in pages:
  these_pages = each.split(",")
  goodset = True
  running = True
#  print(these_pages)
  while running:
#    print(these_pages)
    running = False
    restart = False 
    for p1 in these_pages:
      for p2 in these_pages[these_pages.index(p1):]:
        if p1 != p2:
          pair = f"{p1}|{p2}"
          if pair in rules:
            #print("Good")
            pass
          else:
#            print(these_pages.index(p1))
            p1pos = these_pages.index(p1)
            p2pos = these_pages.index(p2)
            these_pages[p1pos] = p2
            these_pages[p2pos] = p1
#            print(these_pages.index(p1))
            #print("Bad")
            #print(pair)
            running = True
            goodset = False
 #           print("---")
 #           print(these_pages)
  if goodset:
    #print(f"Set {pages.index(each)} is good")
    total += int(these_pages[int((len(these_pages) - 1)/2)])
  else:
    bad_pages.append(these_pages)
    total2 += int(these_pages[int((len(these_pages) - 1)/2)])



for these_pages in bad_pages:
  goodset = True
  running = True
#  print(these_pages)
  while running:
#    print(these_pages)
    running = False
    restart = False 
    for p1 in these_pages:
      for p2 in these_pages[these_pages.index(p1):]:
        if p1 != p2:
          pair = f"{p1}|{p2}"
          if pair in rules:
            #print("Good")
            pass
          else:
            these_pages.append(these_pages.pop(p1))
#            print(these_pages.index(p1))
#            print(these_pages.index(p1))
            #print("Bad")
            #print(pair)
            running = True
            goodset = False
 #           print("---")
 #           print(these_pages)
  total3 += int(these_pages[int((len(these_pages) - 1)/2)])




print(total)
print(total2)
# Part 1 - 7365
#5692 Low
#5700 Low
#5800 Too High
#5750 - Wrong
#5730 - Wrong
print(total3)
## Its not working but the answer for future reference is 5770