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www.mikescher.com/www/statics/aoc/2020/10_solution.rs

104 lines
2.6 KiB
Rust

use crate::common::AdventOfCodeDay;
use itertools::Itertools;
use std::collections::HashMap;
pub struct Day10 {
input: Vec<u32>,
}
impl Day10 {
pub fn new() -> Self {
let input_bytes = include_bytes!("../res/10_input.txt");
let input_str = String::from_utf8_lossy(input_bytes);
let data = input_str
.lines()
.map(|p| p.parse::<u32>().unwrap())
.collect::<Vec<u32>>();
Self {
input: data
}
}
fn path_count(cache: &mut HashMap<usize, u128>, list: &Vec<u32>, idx: usize) -> u128 {
if idx == 0 {
return 1;
}
if let Some(cv) = cache.get(&idx) {
verboseln!("(#) {}", idx);
return *cv;
}
verboseln!("[::] {}", idx);
let mut r = 0;
let me = list[idx];
for delta in 1..4 {
let other_idx = idx as i32 - delta;
if other_idx < 0 {
continue;
}
let other = list[other_idx as usize];
if me - other <= 3 {
r += Day10::path_count(cache, list, other_idx as usize);
}
}
cache.insert(idx, r);
return r;
}
}
impl AdventOfCodeDay for Day10 {
fn task_1(&self) -> String {
let (min, max) = self.input.iter().minmax().into_option().unwrap();
verboseln!("min := {}", min);
verboseln!("max := {}", max);
let diff = self.input
.iter()
.chain([0, *max + 3].iter())
.sorted()
.collect::<Vec<&u32>>()
.windows(2)
.map(|p| p[1] - p[0])
.collect::<Vec<u32>>();
let c1 = diff.iter().filter(|v| **v == 1).count();
let c3 = diff.iter().filter(|v| **v == 3).count();
verboseln!("{} * {} = {}", c1, c3, c1*c3);
return (c1 * c3).to_string() //TODO
}
fn task_2(&self) -> String {
let max = self.input.iter().max().unwrap();
let all = self.input
.iter()
.chain([0, *max + 3].iter())
.sorted()
.map(|p| *p)
.collect::<Vec<u32>>();
let mut hmap: HashMap<usize, u128> = HashMap::new();
//for i in 0..(all.len()) {
// Day10::path_count(&mut hmap, &all, i);
//}
let total = Day10::path_count(&mut hmap, &all, all.len()-1);
return total.to_string();
}
}