my solutions to advent of code
aylac.top
aoc
advent-of-code
1use std::collections::HashSet;
2
3struct Range {
4 start: u64,
5 end: u64,
6}
7
8const MAX_LENGTH: usize = 10;
9
10fn main() {
11 let input: Vec<Range> = include_str!("../../input.txt")
12 .trim()
13 .split(",")
14 .map(|v| {
15 let range = v.split_once("-");
16 match range {
17 Some((start, end)) => Range {
18 start: start.parse().expect("invalid number"),
19 end: end.parse().expect("invalid number"),
20 },
21 _ => panic!("bad input!"),
22 }
23 })
24 .collect();
25
26 let powers_of_ten: Vec<u64> = (0..=MAX_LENGTH as u32).map(|i| 10_u64.pow(i)).collect();
27
28 let [invalid_part_1, invalid_part_2] = {
29 let mut part_1: HashSet<u64> = HashSet::new();
30 let mut part_2: HashSet<u64> = HashSet::new();
31
32 for len in 1..=MAX_LENGTH / 2 {
33 // 1-9, 10-99, 100-999, 100000-999999
34 for combination in
35 *powers_of_ten.get(len - 1).unwrap_or(&1)..*powers_of_ten.get(len).unwrap()
36 {
37 let mut number = 0;
38 // 0 is just the number (9), 1 is one repetition (99)
39 for repeat in 0..MAX_LENGTH / len {
40 number += combination * powers_of_ten.get((len * repeat) as usize).unwrap();
41 if repeat > 0 {
42 part_2.insert(number);
43 }
44 if repeat == 1 {
45 part_1.insert(number);
46 }
47 }
48 }
49 }
50
51 [part_1, part_2]
52 };
53
54 let part_1 = invalid_part_1.iter().fold(0, |acc, number| {
55 if input.iter().any(|r| *number >= r.start && *number <= r.end) {
56 acc + number
57 } else {
58 acc
59 }
60 });
61 println!("{}", part_1);
62
63 let part_2 = invalid_part_2.iter().fold(0, |acc, number| {
64 if input.iter().any(|r| *number >= r.start && *number <= r.end) {
65 acc + number
66 } else {
67 acc
68 }
69 });
70 println!("{}", part_2);
71}