advent_of_code/year2018/
day03.rs

1use crate::input::Input;
2
3struct Fabric {
4    num_claims: Vec<u32>,
5}
6
7struct Claim {
8    id: u32,
9    x: u32,
10    y: u32,
11    width: u32,
12    height: u32,
13}
14
15const SQUARE_WIDTH: u32 = 1000;
16
17impl Fabric {
18    fn from_claims(claims: &[Claim]) -> Self {
19        let mut result = Self {
20            num_claims: vec![0; SQUARE_WIDTH as usize * SQUARE_WIDTH as usize],
21        };
22        claims.iter().for_each(|claim| result.add_claim(claim));
23        result
24    }
25
26    fn add_claim(&mut self, claim: &Claim) {
27        for y in claim.y..claim.y + claim.height {
28            let row_offset = y * 1000;
29            for x in claim.x..claim.x + claim.width {
30                self.num_claims[(row_offset + x) as usize] += 1_u32;
31            }
32        }
33    }
34
35    fn inches_claimed_multiple(&self) -> u32 {
36        self.num_claims.iter().filter(|&&c| c > 1).count() as u32
37    }
38
39    fn is_claimed_once(&self, claim: &Claim) -> bool {
40        let mut result = true;
41        for y in claim.y..claim.y + claim.height {
42            let row_offset = y * 1000;
43            for x in claim.x..claim.x + claim.width {
44                if self.num_claims[(row_offset + x) as usize] > 1 {
45                    result = false;
46                }
47            }
48        }
49        result
50    }
51}
52
53fn parse_input(input_string: &str) -> Result<Vec<Claim>, String> {
54    input_string
55        .lines()
56        .enumerate()
57        .map(|(line_index, line)| {
58            let error_message = || format!("Invalid input on line {}", line_index + 1);
59            let parts: Vec<u32> = line
60                .replace(['#', '@', ':'], "")
61                .replace([',', 'x'], " ")
62                .split_whitespace()
63                .map(|s| s.parse::<u32>().map_err(|_| error_message()))
64                .collect::<Result<_, _>>()?;
65            if parts.len() != 5 {
66                return Err(error_message());
67            }
68            let claim = Claim {
69                id: parts[0],
70                x: parts[1],
71                y: parts[2],
72                width: parts[3],
73                height: parts[4],
74            };
75            if claim.x + claim.width > SQUARE_WIDTH || claim.y + claim.height > SQUARE_WIDTH {
76                return Err(format!(
77                    "Claim outside {SQUARE_WIDTH} by {SQUARE_WIDTH} square"
78                ));
79            }
80            Ok(claim)
81        })
82        .collect()
83}
84
85pub fn solve(input: &Input) -> Result<u32, String> {
86    let claims = parse_input(input.text)?;
87    let fabric = Fabric::from_claims(&claims);
88
89    if input.is_part_one() {
90        Ok(fabric.inches_claimed_multiple())
91    } else {
92        let claim_without_overlap = claims
93            .iter()
94            .find(|claim| fabric.is_claimed_once(claim))
95            .ok_or("No claim without overlap found")?;
96        Ok(claim_without_overlap.id)
97    }
98}
99
100#[test]
101fn tests() {
102    use crate::input::{test_part_one, test_part_two};
103    test_part_one!(
104            "#1 @ 1,3: 4x4
105#2 @ 3,1: 4x4
106#3 @ 5,5: 2x2" => 4
107    );
108
109    test_part_two!(
110            "#1 @ 1,3: 4x4
111#2 @ 3,1: 4x4
112#3 @ 5,5: 2x2"
113        => 3
114    );
115
116    let input = include_str!("day03_input.txt");
117    test_part_one!(input => 104_126);
118    test_part_two!(input => 695);
119}
advent_of_code/year2018/day03.rs

advent_of_code/year2018/
day03.rs
