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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 nom::{Finish, IResult};
@ -15,14 +15,14 @@ fn input_generator(input: &str) -> Vec<String> {
#[aoc(day3, part1)]
fn part1(input: &[String]) -> u32 {
let mut symbol_neighbors = HashSet::new();
for (row, line) in input.iter().enumerate() {
for (col, ch) in line.chars().enumerate() {
if !ch.is_ascii_digit() && ch != '.' {
symbol_neighbors.extend(GridIndex::new(col, row).neighbors());
}
}
}
let symbol_neighbors = input
.iter()
.enumerate()
.flat_map(|(row, line)| {
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;
for (row, line) in input.iter().enumerate() {
let mut col: usize = 0;
@ -32,8 +32,8 @@ fn part1(input: &[String]) -> u32 {
let rest = &line[col..];
let (rem, num) = parse_num(rest).finish().unwrap();
let num_len = rest.len() - rem.len();
for i in 0..num_len {
if symbol_neighbors.contains(&GridIndex::new(col + i, row)) {
for col in col..(col + num_len) {
if symbol_neighbors.contains(&GridIndex::new(col, row)) {
part_sum += num;
break;
}
@ -49,14 +49,14 @@ fn part1(input: &[String]) -> u32 {
#[aoc(day3, part2)]
fn part2(input: &[String]) -> u32 {
let mut gear_locs = Vec::new();
for (row, line) in input.iter().enumerate() {
for (col, ch) in line.chars().enumerate() {
if ch == '*' {
gear_locs.push(GridIndex::new(col, row));
}
}
}
let gear_locs = input
.iter()
.enumerate()
.flat_map(|(row, line)| {
line.match_indices('*')
.map(move |(col, _)| GridIndex::new(col, row))
})
.collect::<Vec<_>>();
let mut gear_neighbor_numbers = HashMap::<usize, Vec<u32>>::new();
for (row, line) in input.iter().enumerate() {
let mut col: usize = 0;
@ -81,12 +81,9 @@ fn part2(input: &[String]) -> u32 {
}
}
}
let mut gear_ratio_sum = 0;
for (_, number_neighbors) in gear_neighbor_numbers.iter() {
if number_neighbors.len() != 2 {
continue;
}
gear_ratio_sum += number_neighbors[0] * number_neighbors[1];
}
gear_ratio_sum
gear_neighbor_numbers
.values()
.filter(|x| x.len() == 2)
.map(|x| x[0] * x[1])
.sum()
}