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use std::collections::HashMap;
static DAY: u8 = 3;
fn main() {
let input = advent::read_lines(DAY);
println!("{DAY}a: {}", part_sum(&input));
println!("{DAY}b: {}", 0);
}
#[derive(Eq, PartialEq, Hash)]
struct Position {
x: isize,
y: isize,
}
struct Schematics {
map: HashMap<Position, char>,
}
impl Schematics {
fn new(input: &[String]) -> Schematics {
let mut map = HashMap::new();
for (y, line) in input.iter().enumerate() {
for (x, c) in line.chars().enumerate() {
if c != '.' {
map.insert(Position { x: x as isize, y: y as isize }, c);
}
}
}
Schematics { map }
}
fn has_neighboring_part(&self, pos: &Position) -> bool {
for y in -1 ..= 1 {
for x in -1 ..= 1 {
if let Some(obj) = self.map.get(&Position { x: pos.x + x, y: pos.y + y }) {
if !obj.is_ascii_digit() {
return true;
}
}
}
}
false
}
}
fn part_sum(input: &[String]) -> u32 {
let schematics = Schematics::new(input);
let mut part_numbers = Vec::new();
for (y, line) in input.iter().enumerate() {
let mut number = 0;
let mut is_part_number = false;
for (x, c) in line.chars().enumerate() {
if let Some(digit) = c.to_digit(10) {
number *= 10;
number += digit;
if schematics.has_neighboring_part(&Position { x: x as isize, y: y as isize }) {
is_part_number = true;
}
} else if number > 0 {
/* number ended within a line */
if is_part_number {
part_numbers.push(number);
}
number = 0;
is_part_number = false;
}
}
if number > 0 && is_part_number {
/* number ended at the end of line */
part_numbers.push(number);
}
}
part_numbers.iter()
.sum()
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test() {
let input = [
"467..114..",
"...*......",
"..35..633.",
"......#...",
"617*......",
".....+.58.",
"..592.....",
"......755.",
"...$.*....",
".664.598..",
].iter().map(|&x| String::from(x)).collect::<Vec<_>>();
assert_eq!(part_sum(&input), 4361);
}
}
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