2018: day03: implement FromStr instead of fn parse

This commit is contained in:
Antoine Martin 2019-11-18 14:27:45 +01:00
parent 8de2538d0e
commit a6ff14b260

View file

@ -1,6 +1,7 @@
use std::collections::HashMap;
use std::collections::HashSet;
use std::error::Error;
use std::str::FromStr;
use super::err;
use super::Result;
@ -22,6 +23,9 @@ struct Claim {
id: usize,
}
impl FromStr for Claim {
type Err = Box<dyn Error>;
/// Parses a claim from a line
///
/// Fails if the line is badly formatted. The expected format is:
@ -29,29 +33,31 @@ struct Claim {
/// ```text
/// #ID @ X,Y: WxH
/// ```
fn parse(line: &str) -> Option<Claim> {
fn from_str(s: &str) -> Result<Self> {
// skip '#' in line
let line = &line[1..];
let s = &s[1..];
// find ' @ ' separator
let at = line.find(" @ ")?;
let id = line[..at].parse().ok()?;
let line = &line[(at + 3)..];
let at = s
.find(" @ ")
.ok_or_else(|| err!("` @ ` delimiter not found"))?;
let id = s[..at].parse()?;
let s = &s[(at + 3)..];
// parse 'X,Y: WxH
let comma = line.find(',')?;
let colon = line.find(':')?;
let x = line[..comma].parse().ok()?;
let y = line[(comma + 1)..colon].parse().ok()?;
let comma = s.find(',').ok_or_else(|| err!("`,` delimiter not found"))?;
let colon = s.find(':').ok_or_else(|| err!("`:` delimiter not found"))?;
let x = s[..comma].parse()?;
let y = s[(comma + 1)..colon].parse()?;
// reduce line to 'WxH'
let line = &line[(colon + 2)..];
let s = &s[(colon + 2)..];
let sep = line.find('x')?;
let width = line[..sep].parse().ok()?;
let height = line[(sep + 1)..].parse().ok()?;
let sep = s.find('x').ok_or_else(|| err!("`x` delimiter not found"))?;
let width = s[..sep].parse()?;
let height = s[(sep + 1)..].parse()?;
Some(Claim {
Ok(Claim {
x,
y,
width,
@ -59,13 +65,16 @@ fn parse(line: &str) -> Option<Claim> {
id,
})
}
}
fn part1(input: &str) -> Result<u64> {
let mut res = 0;
let mut map: HashMap<(usize, usize), u64> = HashMap::new();
for line in input.lines() {
let claim = parse(line).ok_or_else(|| err!("Couldn't parse line: {}", line))?;
let claim: Claim = line
.parse()
.or_else(|e| Err(err!("couldn't parse line: `{}`, {}", line, e)))?;
for i in 0..claim.width {
for j in 0..claim.height {
@ -92,7 +101,9 @@ fn part2(input: &str) -> Result<usize> {
let mut set = HashSet::new();
for line in input.lines() {
let claim = parse(line).ok_or_else(|| err!("Couldn't parse line: {}", line))?;
let claim: Claim = line
.parse()
.or_else(|e| Err(err!("couldn't parse line: `{}`, {}", line, e)))?;
set.insert(claim.id);
for i in 0..claim.width {