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extern crate advent_of_code_2018;
use advent_of_code_2018::*;
use std::error::Error;
use std::path::PathBuf;
use std::slice::Iter;
// cargo watch -cs "cargo run --release --bin day_8"
fn main() -> Result<(), Box<Error>> {
let input: Vec<u32> = read_file(&PathBuf::from("inputs/8.txt"))
.map(|lines| lines[0]
.split_whitespace()
.map(|s| s.parse().unwrap())
.collect()
)?;
//println!("Input: {:?}", input);
let metadata_sum = sum_metadata(&mut input.iter());
debug!(metadata_sum);
let value = node_value(&mut input.iter());
debug!(value);
Ok(())
}
fn sum_metadata(iter: &mut Iter<'_, u32>) -> u32 {
let num_children = iter.next().unwrap().clone();
let num_metadata = iter.next().unwrap().clone();
let children_sum: u32 = (0..num_children)
.map(|_| sum_metadata(iter))
.sum();
let metadata_sum: u32 = (0..num_metadata)
.map(|_| iter.next().unwrap())
.sum();
children_sum + metadata_sum
}
fn node_value(iter: &mut Iter<'_, u32>) -> u32 {
let num_children = iter.next().unwrap().clone();
let num_metadata = iter.next().unwrap().clone();
let node_values: Vec<u32> = (0..num_children)
.map(|_| node_value(iter))
.collect();
let metadata: Vec<u32> = (0..num_metadata)
.map(|_| iter.next().unwrap().clone())
.collect();
if num_children == 0 {
metadata.iter().sum()
} else {
metadata.iter()
.filter(|m| **m > 0 && **m-1 < num_children)
.map(|m| node_values[*m as usize - 1])
.sum()
}
}
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