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Use iterators where possible for day 3

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pjht 2023-12-03 17:42:51 -06:00
parent 9437441dc7
commit f73964c34e
Signed by: pjht
GPG Key ID: 7B5F6AFBEC7EE78E
1 changed files with 24 additions and 27 deletions
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51
src/day03.rs
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@ -1,4 +1,4 @@
use std::collections::{HashMap, HashSet}; use std::collections::HashMap;
use aoc_runner_derive::{aoc, aoc_generator}; use aoc_runner_derive::{aoc, aoc_generator};
use nom::{Finish, IResult}; use nom::{Finish, IResult};
@ -15,14 +15,14 @@ fn input_generator(input: &str) -> Vec<String> {
#[aoc(day3, part1)] #[aoc(day3, part1)]
fn part1(input: &[String]) -> u32 { fn part1(input: &[String]) -> u32 {
let mut symbol_neighbors = HashSet::new(); let symbol_neighbors = input
for (row, line) in input.iter().enumerate() { .iter()
for (col, ch) in line.chars().enumerate() { .enumerate()
if !ch.is_ascii_digit() && ch != '.' { .flat_map(|(row, line)| {
symbol_neighbors.extend(GridIndex::new(col, row).neighbors()); line.match_indices(|ch: char| !ch.is_ascii_digit() && ch != '.')
} .flat_map(move |(col, _)| GridIndex::new(col, row).neighbors())
} })
} .collect::<Vec<_>>();
let mut part_sum = 0; let mut part_sum = 0;
for (row, line) in input.iter().enumerate() { for (row, line) in input.iter().enumerate() {
let mut col: usize = 0; let mut col: usize = 0;
@ -32,8 +32,8 @@ fn part1(input: &[String]) -> u32 {
let rest = &line[col..]; let rest = &line[col..];
let (rem, num) = parse_num(rest).finish().unwrap(); let (rem, num) = parse_num(rest).finish().unwrap();
let num_len = rest.len() - rem.len(); let num_len = rest.len() - rem.len();
for i in 0..num_len { for col in col..(col + num_len) {
if symbol_neighbors.contains(&GridIndex::new(col + i, row)) { if symbol_neighbors.contains(&GridIndex::new(col, row)) {
part_sum += num; part_sum += num;
break; break;
} }
@ -49,14 +49,14 @@ fn part1(input: &[String]) -> u32 {
#[aoc(day3, part2)] #[aoc(day3, part2)]
fn part2(input: &[String]) -> u32 { fn part2(input: &[String]) -> u32 {
let mut gear_locs = Vec::new(); let gear_locs = input
for (row, line) in input.iter().enumerate() { .iter()
for (col, ch) in line.chars().enumerate() { .enumerate()
if ch == '*' { .flat_map(|(row, line)| {
gear_locs.push(GridIndex::new(col, row)); line.match_indices('*')
} .map(move |(col, _)| GridIndex::new(col, row))
} })
} .collect::<Vec<_>>();
let mut gear_neighbor_numbers = HashMap::<usize, Vec<u32>>::new(); let mut gear_neighbor_numbers = HashMap::<usize, Vec<u32>>::new();
for (row, line) in input.iter().enumerate() { for (row, line) in input.iter().enumerate() {
let mut col: usize = 0; let mut col: usize = 0;
@ -81,12 +81,9 @@ fn part2(input: &[String]) -> u32 {
} }
} }
} }
let mut gear_ratio_sum = 0; gear_neighbor_numbers
for (_, number_neighbors) in gear_neighbor_numbers.iter() { .values()
if number_neighbors.len() != 2 { .filter(|x| x.len() == 2)
continue; .map(|x| x[0] * x[1])
} .sum()
gear_ratio_sum += number_neighbors[0] * number_neighbors[1];
}
gear_ratio_sum
} }