Advent of Code 2022, Day 14

Ramen Junkie December 14, 2022 0Comment

Man, I really enjoyed today’s puzzle. Like, a lot. I think because it kind of felt like a game level, and probably also because it’s fluid dynamics and I am totally into Physics and Engineering shit.

For the “Plot” you enter into a cave and discover a cavern with sand falling from the ceiling. The sand accumulates in a pile and “flows” around based on some simple left then right rules. This problem consisted of a few separate but connected steps.

Step one, create an empty “cave”. This was simple enough, especially now that I remember how stupid lists are. Last time I needed to make a grid, I was appending a list and it turns out that Python doesn’t actually copy lists unless you explicitly ask it to. Which is frankly, “Fucking Stupid”. But whatever, list.copy() works too.

Step 2, draw the rocks from the input file. Each line consists of a start note, then a series of connected dots to the end point of a line of rocks.

Step 3, was to pour the sand. Which involves dropping a “chunk” of sand, down until it hits the floor, then flowing it left or right to fill an area. Once the sand starts falling off, then display the count of the total chunks. If I were more clever about my code, I could build a sweet little ASCII animation of each step, but I probably won’t anytime soon because well, I have other things I need to do too.

Part 2 modifies this, by adding a floor, instead of counting the amount of sand until it fills, and falls into the abyss below, now you count until it fills then fills all the way back to the top. This actually screwed me up a bit.

The coordinates given are all large, like, in the 500 range. In order to make my rock formation manageable, I had cut these down by the min max values so the cave was not much wider than the rock formation. The problem is, now I need to accumulate a pile across the floor, so I need the width. Like, a LOT of width. So I had to modify my code all over to bring the width back to my cave matrix.

The code works for Part 1 and Part 2 at once. Basically, it finishes Part 1, like normal, display the output count, and, just for fun, an ASCII image of the filled rocks, then, it just, starts a fresh, slightly modified loop. For the modified loop, the break for “falling off” is removed. Instead, it checks to see if it can move, and if it can’t, before placing the sand block, it verifies if it moved at all by comparing it’s position to the start position. If it hasn’t moved, it breaks the loop, prints the filled screen, and the sand count total.

import math

with open("Day14Input.txt") as file:
    data = file.read()

lines = data.split('\n')

def draw_cave(lx, ly):
    grid = []
    line = []
    floor = []
    for i in range(0,lx*2):
        line.append(".")
    for j in range(0,ly+2):
        grid.append(line.copy())
    for i in range(0, lx * 2):
        floor.append("#")
    grid.append(floor)
    return grid

def draw_rocks(rocks,cave):
    for rockline in rocks:
        for i in range(len(rockline)-1):
            startx = int(rockline[i][0])
            starty = int(rockline[i][1])
            endx = int(rockline[i+1][0])
            endy = int(rockline[i+1][1])
            if starty == endy:
                xrange = sorted([startx, endx])
                for horiz in range(xrange[0],xrange[1]+1):
                    cave[starty][horiz] = "#"
            if startx == endx:
                yrange = sorted([starty, endy])
                for vert in range(yrange[0], yrange[1]+1):
                    cave[vert][startx] = "#"
    return cave

def show_cave():
    for i in cave:
        print(" ".join(i))

smallest_x = 100000
smallest_y = 100000
largest_x = -1
largest_y = -1
rocks = []
for line in lines:
    sets = line.split(" -> ")
    r = []
    for n in sets:
        nsplit = n.split(",")
        if int(nsplit[0]) < smallest_x:
            smallest_x = int(nsplit[0])
        if int(nsplit[1]) < smallest_y:
            smallest_y = int(nsplit[1])
        if int(nsplit[0]) > largest_x:
            largest_x = int(nsplit[0])
        if int(nsplit[1]) > largest_y:
            largest_y = int(nsplit[1])
        r.append(n.split(","))
    rocks.append(r)

# print(f"{smallest_x} {largest_x} | {smallest_y} {largest_y}")
# print(rocks)

cave = draw_cave(largest_x,largest_y)
# show_cave()
rocky_cave = draw_rocks(rocks,cave)

sand_start = 500
rocky_cave[0][sand_start] = "+"

captured = True
sand_count = 0
while captured:
    sand_pos = [0,sand_start]

    sand_drop = True
    while sand_drop:
        if sand_pos[0] > len(rocky_cave)-3:
            captured = False
            sand_drop = False
        elif rocky_cave[sand_pos[0]+1][sand_pos[1]] == ".":
            sand_pos[0] += 1
        elif rocky_cave[sand_pos[0]+1][sand_pos[1]-1] == ".":
                sand_pos[0] += 1
                sand_pos[1] -= 1
        elif rocky_cave[sand_pos[0]+1][sand_pos[1]+1] == ".":
                sand_pos[0] += 1
                sand_pos[1] += 1
        else:
            sand_count+=1
            rocky_cave[sand_pos[0]][sand_pos[1]] = "O"
            sand_drop = False

    # show_cave()

print(sand_count)
show_cave()
# Part 1 = 728

#### RESUME FOR PART 2 #####
captured = True
while captured:
    sand_pos = [0,sand_start]

    sand_drop = True
    while sand_drop:
        if sand_pos[0] > len(rocky_cave)-1:
            captured = False
            sand_drop = False
        elif rocky_cave[sand_pos[0]+1][sand_pos[1]] == ".":
            sand_pos[0] += 1
        elif rocky_cave[sand_pos[0]+1][sand_pos[1]-1] == ".":
                sand_pos[0] += 1
                sand_pos[1] -= 1
        elif rocky_cave[sand_pos[0]+1][sand_pos[1]+1] == ".":
                sand_pos[0] += 1
                sand_pos[1] += 1
        else:
            if sand_pos == [0,sand_start]:
                captured = False
            else:
                rocky_cave[sand_pos[0]][sand_pos[1]] = "O"
            sand_count+=1
            sand_drop = False

print(sand_count)

show_cave()
# Part 2 = 27623

Advent of Code 2022, Day 13

Ramen Junkie December 13, 2022 0Comment

Have I ever mentioned before how much I hate Recursion?

So, I feel like I mentioned on a previous Advent of Code post, half the problem of these puzzles is figuring out how to massage the input. Which I started to work with until I found the eval() function, which I don’t recall using before. But it basically will take something like a string that looks like a list, say, “[2,[4,5,6]]” and make it into a list of lists. Which solved the first problem I had.

Then there was the checks itself. The puzzle was a series of lists full of lists and integers, that needed to be sorted based on some criteria. It basically amounts to a series of if checks, if the data is a list or an int and what to do, if the lengths are the same or different, if one value is larger than the other. Except it can be lists in lists, hence the need for recursion. I felt like I was really close, but then scrapped that for a new approach. Then I got stuck again, then I realized I needed to loop through the internal list. Everything eventually lined up for part 1 nicely.

On to Part 2. Which basically amounts to, using the algorithm on the entire list, instead of just pairs.

I was actually a bit disappointed because I was sure I had come up with a clever way to solve this without the sorting algorithm. I left it in the code, but it’s not used. Here it is anyway.

## Not Used But This really feels like it should have worked.
def decoder(decode_list):
    new_list = []
    for each in decode_list:
        each = each.replace("[]", "0")
        each = each.replace("[", "")
        each = each.replace("]", "")
        each = each.replace(",", "")
        new_list.append(int(each[0]))
    new_list.sort()
    print(new_list)
    print((new_list.index(6)+1)*(new_list.index(2)+1))

The idea was, that I would flatten each list out to an integer, then sort the data that way. The target values needed were simply, 2 and 6. The initial sort put 2 and 6 at basically positions 2 and 6. because 2 is less than 200 when sorting. So it dawned on me, that 2 and 6, would always be the “first” at the “start of the 2s” and “start of the 6s”. So the I just added the first digit to the list, then sorted that, and took the first 2 and first 6. And it still didn’t work.

Figures it wouldn’t be that simple.

While contemplating using nested for loops, I decided to check some other solutions, and found something I had not used before, “cmp_to_key”. After reading up on it, it seems it can be used with the sort function to generate sorts based on a key value returned from a function.

So I modified my sort unction to use +1, -1, and 0 instead of True and False.

Aaaaand, it still didn’t sort, it wasn’t sorting. I had forgotten that I needed to use eval() on each entry, to turn it into Lists instead of Strings. My sort wasn’t working because it doesn’t work on Strings. So I corrected that and bam! Working.

from functools import cmp_to_key

with open("Day13Input.txt") as file:
    data = file.read()

split_data = data.split("\n\n")
decode_data = []
for line in data.replace("\n\n", "\n").split("\n"):
    decode_data.append(eval(line))

def compare_lists(left,right):
    # print(left)
    # print(right)

    if isinstance(left, int) and isinstance(right, int):
        # print(f"{left} {right}")
        if left < right:
            return 1
        elif left > right:
            return -1
        return 0

    if isinstance(left, list) and isinstance(right, list):
        for value in range(min(len(left), len(right))):
            check_value = (compare_lists(left[value], right[value]))
            # print(f"{left[value]} {right[value]}")
            # print(check_value)
            if check_value != 0:
                return check_value

        if len(left) < len(right):
            return 1
        elif len(left) > len(right):
            return -1
    if isinstance(left, int) and isinstance(right, list):
        return compare_lists([left], right)
    if isinstance(left, list) and isinstance(right, int):
        return compare_lists(left, [right])

    return 0

## Not Used But This really feels like it should have worked.
def decoder(decode_list):
    new_list = []
    for each in decode_list:
        each = each.replace("[]", "0")
        each = each.replace("[", "")
        each = each.replace("]", "")
        each = each.replace(",", "")
        new_list.append(int(each[0]))
    new_list.sort()
    print(new_list)
    print((new_list.index(6)+1)*(new_list.index(2)+1))

index_sum = 0
for i in range(len(split_data)-1):
    set1 = split_data[i].split("\n")[0]
    set2 = split_data[i].split("\n")[1]

    match = compare_lists(eval(set1), eval(set2))
    # print(match)

    if match == 1:
        index_sum += (i+1)


print(index_sum)
# 6373 Too high
# 5997 Too low
# 6187

decode_data.append([[2]])
decode_data.append([[6]])
#decoder(decode_data)
decode_data.sort(key=cmp_to_key(compare_lists), reverse=True)
# for each in decode_data:
#     print(each)
print((decode_data.index([[2]])+1)*(decode_data.index([[6]])+1))

# 23520