mx42/aoc2024.rs
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feat: day 11 p2

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Yoru
2024-12-12 12:51:32 +01:00
parent 6dc9d891b5
commit 056c79168f
3 changed files with 138 additions and 29 deletions
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69
src/bin/11.rs
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@@ -1,42 +1,63 @@
advent_of_code::solution!(11);
use std::iter::successors;
use memoize::memoize;
fn update_stones(stones: &Vec<u64>) -> Vec<u64> {
stones.into_iter().flat_map(|st|
match (st, st.checked_ilog10().unwrap_or(0) + 1) {
(0, _) => vec![1],
(n, digits) if digits % 2 == 0 && digits > 0 => {
let div = 10u64.pow(digits / 2);
vec![
n / div,
n % div,
]
},
_ => vec![st * 2024],
#[memoize]
fn get_child_stones_count(stone: u64, depth: u8) -> usize {
if depth == 0 {
return 1;
}
let digits = stone.checked_ilog10().unwrap_or(0) + 1;
match (stone, digits) {
(0, _) => get_child_stones_count(1, depth - 1),
(n, digits) if digits % 2 == 0 && digits > 0 => {
let div = 10u64.pow(digits / 2);
get_child_stones_count(n / div, depth - 1) + get_child_stones_count(n % div, depth - 1)
}
).collect()
_ => get_child_stones_count(stone * 2024, depth - 1),
}
}
// fn update_stones(stones: &Vec<u64>) -> Vec<u64> {
// stones.into_iter().flat_map(|st|
// match (st, st.checked_ilog10().unwrap_or(0) + 1) {
// (0, _) => vec![1],
// (n, digits) if digits % 2 == 0 && digits > 0 => {
// let div = 10u64.pow(digits / 2);
// vec![
// n / div,
// n % div,
// ]
// },
// _ => vec![st * 2024],
// }
// ).collect()
// }
fn parse_input(input: &str) -> Result<Vec<u64>, std::num::ParseIntError> {
input.split_whitespace().map(|c| c.parse::<u64>()).collect()
}
pub fn part_one(input: &str) -> Option<usize> {
let stones = parse_input(input).ok()?;
successors(Some(stones), |st| Some(update_stones(st)))
.nth(25)
.unwrap()
.len()
parse_input(input)
.ok()?
.into_iter()
.map(|st| get_child_stones_count(st, 25))
.sum::<usize>()
.into()
// successors(Some(stones), |st| Some(update_stones(st)))
// .nth(25)
// .unwrap()
// .len()
// .into()
}
pub fn part_two(input: &str) -> Option<usize> {
let stones = parse_input(input).ok()?;
successors(Some(stones), |st| Some(update_stones(st)))
.nth(75)
.unwrap()
.len()
parse_input(input)
.ok()?
.into_iter()
.map(|st| get_child_stones_count(st, 75))
.sum::<usize>()
.into()
}