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Day 8 part 2 perf improvements with s/HashSet/Vec/ and others

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This commit is contained in:
Bill Thiede 2021-12-08 18:16:15 -08:00
parent 19ca505fde
commit b15a06e07c
1 changed files with 12 additions and 17 deletions
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29
2021/src/day8.rs
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@ -117,7 +117,7 @@
//! For each entry, determine all of the wire/segment connections and decode the four-digit output values. What do you get if you add up all of the output values?
//!
use std::{
collections::{HashMap, HashSet},
collections::HashMap,
convert::Infallible,
fmt::{Debug, Error, Formatter},
ops::BitAnd,
@ -158,7 +158,7 @@ impl FromStr for Segment {
fn from_str(s: &str) -> Result<Self, Self::Err> {
let mut bits = 0;
for b in s.as_bytes() {
bits |= 1 << b - b'a';
bits |= 1 << (b - b'a');
}
Ok(Segment(bits))
@ -176,18 +176,18 @@ impl BitAnd for Segment {
fn build_lookup(input: &str) -> Result<HashMap<Segment, u8>> {
let mut map: HashMap<u8, Segment> = HashMap::new();
let set: HashSet<_> = input.split(' ').collect();
let set: Vec<_> = input.split(' ').collect();
for digit in &set {
let d = digit.parse().unwrap();
let s = digit.parse().unwrap();
match digit.len() {
// 1
2 => map.insert(1, d),
2 => map.insert(1, s),
// 7
3 => map.insert(7, d),
3 => map.insert(7, s),
// 4
4 => map.insert(4, d),
4 => map.insert(4, s),
// 8
7 => map.insert(8, d),
7 => map.insert(8, s),
_ => None,
};
}
@ -232,18 +232,13 @@ fn build_lookup(input: &str) -> Result<HashMap<Segment, u8>> {
fn output(line: &str) -> Result<u64> {
let (inp, out) = line.split_once(" | ").expect("line missing |");
let lookup = build_lookup(inp)?;
let mut answer = 0;
for digit in out
Ok(out
.split(' ')
.map(|s| {
let s: Segment = s.parse()?;
Ok(lookup[&s])
let s: Segment = s.parse().unwrap();
lookup[&s]
})
.collect::<Result<Vec<_>>>()?
{
answer = 10 * answer + digit as u64;
}
Ok(answer)
.fold(0, |answer, d| 10 * answer + d as u64))
}
#[aoc(day8, part2)]