bwc9876.dev
Advent of Code solutions
Day 2
+57
-5
+1
Cargo.lock
+1
Cargo.lock
+1
years/2025/Cargo.toml
+1
years/2025/Cargo.toml
+49
-5
years/2025/src/day_2.rs
+49
-5
years/2025/src/day_2.rs
···
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use std::ops::RangeInclusive;
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use advent_core::{Day, day_stuff, ex_for_day};
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use utils::num::{num_digits, split_num_at, split_num_once};
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pub struct Day2;
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impl Day for Day2 {
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day_stuff!(2, "1227775554", "4174379265", Vec<RangeInclusive<usize>>);
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day_stuff!(2, "", "");
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fn part_1(input: Self::Input) -> Option<String> {
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let ans = input
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.into_iter()
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.flat_map(|r| {
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r.into_iter().filter(|x| {
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let (l, r) = split_num_once(*x);
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l == r
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})
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})
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.sum::<usize>();
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fn part_1(_input: Self::Input) -> Option<String> {
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None
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Some(ans.to_string())
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}
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fn part_2(_input: Self::Input) -> Option<String> {
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None
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fn part_2(input: Self::Input) -> Option<String> {
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let ans = input
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.into_iter()
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.flat_map(|r| {
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r.into_iter().filter(|x| {
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let digs = num_digits(*x);
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(2..=digs).into_iter().filter(|n| digs % n == 0).any(|n| {
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let mut parts = Vec::with_capacity(n);
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let mut current = *x;
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let split_at = digs / n;
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for _ in 0..n {
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let (rest, part) = split_num_at(current, split_at as u32);
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parts.push(part);
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current = rest;
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}
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parts
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.first()
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.copied()
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.map_or(false, |first| parts.into_iter().all(|x| x == first))
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})
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})
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})
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.sum::<usize>();
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Some(ans.to_string())
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}
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fn parse_input(input: &str) -> Self::Input {
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input
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.split(',')
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.map(|r| {
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let (l, r) = r.split_once('-').unwrap();
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(l.trim().parse::<usize>().unwrap())..=(r.trim().parse::<usize>().unwrap())
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})
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.collect()
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}
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}
+3
years/2025/src/examples/day_2/1.txt
+3
years/2025/src/examples/day_2/1.txt