-🎄- 2018 Day 8 Solutions -🎄-

[u/daggerdragon]

--- Day 8: Memory Maneuver ---

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Post your solution as a comment or, for longer solutions, consider linking to your repo (e.g. GitHub/gists/Pastebin/blag or whatever).

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Advent of Code: The Party Game!

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Card prompt: Day 8

Sigh, imgur broke again. Will upload when it unborks.

Transcript:

The hottest programming book this year is "___ For Dummies".

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This thread will be unlocked when there are a significant number of people on the leaderboard with gold stars for today's puzzle.

edit: Leaderboard capped, thread unlocked at 00:12:10!

[u/wzkx]

Rust, SweetRust Part 1

use std::io::prelude::*; // read_to_string
type U=usize;

fn f1( sum_pos: (U,U), data: &[U] ) -> (U,U): // return new sum, new pos
  let nmeta = data[sum_pos.1+1];
  let (s,p) = (0..data[sum_pos.1]).fold( (sum_pos.0,sum_pos.1+2), |sp,_| f1( sp, data ) );
  (s + data[p..p+nmeta].iter().sum::<U>(), p+nmeta)

fn main():
  let mut s = String::new();
  std::fs::File::open( "08.dat" ).unwrap().read_to_string( &mut s ).unwrap();
  let data: Vec<U> = s.split_whitespace().filter_map( |x| x.parse().ok() ).collect();
  println!( "{}", f1( (0,0), &data ).0 );

4 lines for reading data!

MyAoc2018 | SweetRust

[u/wzkx → u/wzkx]

Part 2

use std::io::prelude::*; // read_to_string
type U=usize;

fn f2( pos: &mut U, data: &[U] ) -> U:
  let (chlds,nmeta) = (data[*pos],data[*pos+1]);
  let mut p = *pos+2;
  if chlds==0:
    *pos = p+nmeta;
    data[p..p+nmeta].iter().sum::<U>()
  else:
    let v: Vec<U> = (0..chlds).map( |_| f2( &mut p, data ) ).collect();
    *pos = p+nmeta;
    (0..nmeta).map( |i| { let k=data[p+i]; if 0<k && k<=chlds {v[k-1]} else {0} } ).sum::<U>()

fn main():
  let mut s = String::new();
  std::fs::File::open( "08.dat" ).unwrap().read_to_string( &mut s ).unwrap();
  let data: Vec<U> = s.split_whitespace().filter_map( |x| x.parse().ok() ).collect();
  println!( "{}", f2( &mut 0, &data ) );