2018: day03: part 1

This commit is contained in:
Antoine Martin 2019-11-15 16:11:58 +01:00
parent 0968951383
commit cf17d2779c
3 changed files with 1451 additions and 0 deletions

1347
aoc2018/input/day03.txt Normal file

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103
aoc2018/src/day03.rs Normal file
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use std::collections::HashMap;
use std::fmt;
use super::Result;
const INPUT: &str = include_str!("../input/day03.txt");
pub fn run() -> Result<()> {
println!("part 1: {}", part1(INPUT)?);
Ok(())
}
#[derive(Debug)]
struct ParseError {
line: String,
}
impl ParseError {
fn new(line: &str) -> Self {
ParseError {
line: line.to_string(),
}
}
}
impl fmt::Display for ParseError {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "{}", self.line)
}
}
impl std::error::Error for ParseError {
fn description(&self) -> &str {
&self.line
}
}
fn parse(line: &str) -> Option<(usize, usize, usize, usize)> {
// remove '#XXX @ ' start of line
let line = &line[(line.find(" @ ")? + 3)..];
// parse 'x,y: NNxNN
let comma = line.find(',')?;
let colon = line.find(':')?;
let x = line[..comma].parse().ok()?;
let y = line[(comma + 1)..colon].parse().ok()?;
// reduce line to 'NNxNN'
let line = &line[(colon + 2)..];
let sep = line.find('x')?;
let width = line[..sep].parse().ok()?;
let height = line[(sep + 1)..].parse().ok()?;
Some((x, y, width, height))
}
fn part1(input: &str) -> Result<u64> {
let mut res = 0;
let mut map: HashMap<(usize, usize), u64> = HashMap::default();
for line in input.lines() {
let (x, y, width, height) = parse(line).ok_or(ParseError::new(line))?;
for i in 0..width {
for j in 0..height {
let x = x + i;
let y = y + j;
// add tissue patch at coordinates (x, y)
let entry = map.entry((x, y)).or_default();
*entry += 1;
// count overlap the first time only
if *entry == 2 {
res += 1;
}
}
}
}
Ok(res)
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn part1_provided() {
let input = "#1 @ 1,3: 4x4
#2 @ 3,1: 4x4
#3 @ 5,5: 2x2
";
assert_eq!(part1(input).unwrap(), 4);
}
#[test]
fn part1_real() {
assert_eq!(part1(INPUT).unwrap(), 114946);
}
}

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pub mod day01; pub mod day01;
pub mod day02; pub mod day02;
pub mod day03;
pub type Result<T> = std::result::Result<T, Box<dyn std::error::Error>>; pub type Result<T> = std::result::Result<T, Box<dyn std::error::Error>>;