Day 11: Cosmic Expansion

Megathread guidelines

  • Keep top level comments as only solutions, if you want to say something other than a solution put it in a new post. (replies to comments can be whatever)
  • Code block support is not fully rolled out yet but likely will be in the middle of the event. Try to share solutions as both code blocks and using something such as https://topaz.github.io/paste/ , pastebin, or github (code blocks to future proof it for when 0.19 comes out and since code blocks currently function in some apps and some instances as well if they are running a 0.19 beta)

FAQ

🔒 Thread is locked until there’s at least 100 2 star entries on the global leaderboard

🔓 Unlocked after 9 mins

  • @[email protected]
    2•1 year ago

    I saw that coming, but decided to do it the naive way for part 1, then fixed that up for part 2. Thanks to AoC I can also recognise a Manhattan distance written in a complex manner.

    Python 
    from __future__ import annotations

import re
import math
import argparse
import itertools

def print_sky(sky:list):
    for r in sky:
        print("".join(r))

class Point:
    def __init__(self,x:int,y:int) -> None:
        self.x = x
        self.y = y

    def __repr__(self) -> str:
        return f"Point({self.x},{self.y})"

    def distance(self,point:Point):
        # Manhattan dist
        x = abs(self.x - point.x)
        y = abs(self.y - point.y)
        return x + y

def expand_galaxies(galaxies:list,position:int,amount:int,index:str):
    for g in galaxies:
        if getattr(g,index) > position:
            c = getattr(g,index)
            setattr(g,index, c + amount)

def main(line_list:list,part:int):
    ## list of lists is the plan for init idea

    expand_value = 2 -1
    if part == 2:
        expand_value = 1e6 -1
    if part > 2:
        expand_value = part -1

    sky = list()
    for l in line_list:
        row_data = [*l]
        sky.append(row_data)
    
    print_sky(sky)
    
    # get galaxies
    gal_list = list()
    for r in range(0,len(sky)):
        for c in range(0,len(sky[r])):
            if sky[r][c] == '#':
                gal_list.append(Point(r,c))

    print(gal_list)

    col_indexes = list(reversed(range(0,len(sky))))
    # expand rows
    for i in col_indexes:
        if not '#' in sky[i]:
            expand_galaxies(gal_list,i,expand_value,'x')

    # check for expanding columns
    for i in reversed( range(0, len( sky[0] )) ):
        col = [sky[x][i] for x in col_indexes]
        if not '#' in col:
            expand_galaxies(gal_list,i,expand_value,'y')

    print(gal_list)

    # find all unique pair distance sum, part 1
    sum = 0
    for i in range(0,len(gal_list)):
        for j in range(i+1,len(gal_list)):
            sum += gal_list[i].distance(gal_list[j])

    print(f"Sum distances: {sum}")

if __name__ == "__main__":
    parser = argparse.ArgumentParser(description="template for aoc solver")
    parser.add_argument("-input",type=str)
    parser.add_argument("-part",type=int)
    args = parser.parse_args()
    filename = args.input
    if filename == None:
        parser.print_help()
        exit(1)
    part = args.part
    file = open(filename,'r')
    main([line.rstrip('\n') for line in file.readlines()],part)
    file.close()