14.md

Day 14

	Part 1	Part 2	Total
Time	14:56	2:06	17:02

That's more like it! Rank 295 for Part 1, 205 for Part 2. This is the first time I've placed well in both parts. This one was refreshing after a couple of slow days for me.

The above visualization is for Part 2.

Part 1

This was a puzzle where you just have to do it. I decided to store the rock walls in a defaultdict and do nested while loops for the falling sand. When the sand stopped moving, I just treated it like a rock. All I had to do was break out of the outer loop when a peice of sand falls below the lowest point added during the rock wall creation stage.

from helpers.datagetter import data_in, submit
from collections import defaultdict

ans = -1
din = data_in(split=True, numbers=False)

rock = defaultdict(int)
lowest = 0

for line in din:
    pts = line.split(" -> ")
    for i in range(len(pts)-1):
        first = eval("[" + pts[i] + "]")
        second = eval("[" + pts[i+1] + "]")
        if first[0] == second[0]:
            for j in range(min(first[1], second[1]), max(first[1], second[1])+1):
                rock[f"{first[0]},{j}"] = 1
                lowest = max(lowest, j)
        elif first[1] == second[1]:
            for j in range(min(first[0], second[0]), max(first[0], second[0])+1):
                rock[f"{j},{first[1]}"] = 1
                lowest = max(lowest, first[1])

print(len(rock.values()))
found = False
while not found:
    sx = 500
    sy = 0

    while True:
        if sy >= lowest:
            found = True
            break

        if rock[f"{sx},{sy+1}"] == 0:
            sy += 1
        else:
            if rock[f"{sx-1},{sy+1}"] == 0:
                sy += 1
                sx -= 1
            elif rock[f"{sx+1},{sy+1}"] == 0:
                sy += 1
                sx += 1
            else:
                rock[f"{sx},{sy}"] = 1
                break

    ans += 1

print(ans)
submit(ans)

Part 2

For this part, it was as simple as adding a condition to place the sand when it checks at lowest + 1 since there is now a floor at lowest + 2. And the new break out condition for the outer loop is as soon as a unit of sand is placed at (500, 0).

# REPLACE NESTED WHILE LOOPS WITH THIS

while True:
    sx = 500
    sy = 0

    while True:
        if sy >= lowest + 1:
            rock[f"{sx},{sy}"] = 1
            break

        if rock[f"{sx},{sy+1}"] == 0:
            sy += 1
        else:
            if rock[f"{sx-1},{sy+1}"] == 0:
                sy += 1
                sx -= 1
            elif rock[f"{sx+1},{sy+1}"] == 0:
                sy += 1
                sx += 1
            else:
                rock[f"{sx},{sy}"] = 1
                break

    if sx == 500 and sy == 0:
        break
    ans += 1
    
ans += 2 # Because of where I placed the increment of ans
print(ans)
submit(ans)