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Advent of Code solutions
1use advent_core::{day_stuff, ex_for_day, Day};
2
3pub struct Day3;
4
5impl Day for Day3 {
6 day_stuff!(3, "357", "3121910778619", Vec<Vec<usize>>);
7
8 fn part_1(input: Self::Input) -> Option<String> {
9 let ans = input
10 .into_iter()
11 .map(|bank| {
12 let (largest_idx, largest) = bank
13 .iter()
14 .enumerate()
15 .take(bank.len() - 1)
16 .rev()
17 .max_by(|(_, x), (_, y)| (**x).cmp(*y))
18 .map(|(i, x)| (i, *x))
19 .unwrap();
20 let rest = bank.into_iter().skip(largest_idx + 1);
21 let next_largest = rest.max().unwrap();
22 largest * 10 + next_largest
23 })
24 .sum::<usize>();
25
26 Some(ans.to_string())
27 }
28
29 fn part_2(input: Self::Input) -> Option<String> {
30 let ans = input
31 .into_iter()
32 .map(|bank| {
33 let mut num = 0;
34 let mut start = 0;
35
36 for i in 0..12 {
37 let (idx, largest) = bank
38 .iter()
39 .enumerate()
40 .filter(|(idx, _)| {
41 (i == 0 || *idx > start) && *idx + (11 - i) <= (bank.len() - 1)
42 })
43 .rev()
44 .max_by(|(_, x), (_, y)| (**x).cmp(*y))
45 .map(|(idx, x)| (idx, *x))
46 .unwrap();
47
48 num += largest * 10_usize.pow((11 - i) as u32);
49 start = idx;
50 }
51
52 num
53 })
54 .sum::<usize>();
55
56 Some(ans.to_string())
57 }
58
59 fn parse_input(input: &str) -> Self::Input {
60 input
61 .lines()
62 .map(|l| {
63 l.trim()
64 .chars()
65 .map(|c| c.to_digit(10).unwrap() as usize)
66 .collect()
67 })
68 .collect()
69 }
70}