From 989fc854d9afe94ea5578ed31ee498f5839ab660 Mon Sep 17 00:00:00 2001 From: Antoine Martin Date: Fri, 6 Dec 2019 19:47:25 +0100 Subject: [PATCH] 2019: day03: parse input only once --- aoc2019/src/day03.rs | 126 +++++++++++++++++-------------------------- 1 file changed, 48 insertions(+), 78 deletions(-) diff --git a/aoc2019/src/day03.rs b/aoc2019/src/day03.rs index 5a686bc..8db70e6 100644 --- a/aoc2019/src/day03.rs +++ b/aoc2019/src/day03.rs @@ -12,8 +12,10 @@ const INPUT: &str = include_str!("../input/day03.txt"); pub fn run() -> Result { let mut res = String::with_capacity(128); - writeln!(res, "part 1: {}", part1(INPUT)?)?; - writeln!(res, "part 2: {}", part2(INPUT)?)?; + let (first, second) = parse_paths(INPUT)?; + + writeln!(res, "part 1: {}", part1(&first, &second)?)?; + writeln!(res, "part 2: {}", part2(&first, &second)?)?; Ok(res) } @@ -50,72 +52,7 @@ impl FromStr for Move { } } -fn path(mut a: (i64, i64), b: (i64, i64)) -> Vec<(i64, i64)> { - let mut res = Vec::new(); - - while a != b { - if a.0 < b.0 { - a.0 += 1; - } else if a.0 > b.0 { - a.0 -= 1; - } - - if a.1 < b.1 { - a.1 += 1; - } else if a.1 > b.1 { - a.1 -= 1; - } - - res.push(a); - } - - res -} - -fn parse_path(line: &str) -> Result> { - let moves = line - .trim_end() - .split(',') - .map(|m| m.parse()) - .collect::>>()?; - - let mut pos = (0, 0); - - Ok(moves - .iter() - .flat_map(|mv| { - let new_pos = match mv { - Move::Up(dy) => (pos.0, pos.1 - dy), - Move::Down(dy) => (pos.0, pos.1 + dy), - Move::Left(dx) => (pos.0 - dx, pos.1), - Move::Right(dx) => (pos.0 + dx, pos.1), - }; - - let p = path(pos, new_pos); - pos = new_pos; - p - }) - .collect()) -} - -fn manhattan_distance(a: (i64, i64), b: (i64, i64)) -> i64 { - (a.0 - b.0).abs() + (a.1 - b.1).abs() -} - -fn part1(input: &str) -> Result { - let mut lines = input.lines(); - let first_path = parse_path(lines.next().ok_or_else(|| err!("missing line in input"))?)?; - let second_path = parse_path(lines.next().ok_or_else(|| err!("missing line in input"))?)?; - - let cross_locations = first_path.intersection(&second_path); - - cross_locations - .map(|(x, y)| manhattan_distance((*x, *y), (0, 0))) - .min() - .ok_or_else(|| err!("the cables never crossed !")) -} - -fn path_count(mut a: (i64, i64), b: (i64, i64), mut start_count: i64) -> Vec<((i64, i64), i64)> { +fn path_count(mut a: (i64, i64), b: (i64, i64), mut start_count: u64) -> Vec<((i64, i64), u64)> { let mut res = Vec::new(); while a != b { @@ -138,7 +75,7 @@ fn path_count(mut a: (i64, i64), b: (i64, i64), mut start_count: i64) -> Vec<((i res } -fn parse_path_with_count(line: &str) -> Result> { +fn parse_path_with_count(line: &str) -> Result> { let moves = line .trim_end() .split(',') @@ -166,13 +103,38 @@ fn parse_path_with_count(line: &str) -> Result> { .collect()) } -fn part2(input: &str) -> Result { +fn parse_paths(input: &str) -> Result<(HashMap<(i64, i64), u64>, HashMap<(i64, i64), u64>)> { let mut lines = input.lines(); let first_path = parse_path_with_count(lines.next().ok_or_else(|| err!("missing line in input"))?)?; let second_path = parse_path_with_count(lines.next().ok_or_else(|| err!("missing line in input"))?)?; + Ok((first_path, second_path)) +} + +fn manhattan_distance(a: (i64, i64), b: (i64, i64)) -> u64 { + (a.0 - b.0).abs() as u64 + (a.1 - b.1).abs() as u64 +} + +fn part1( + first_path: &HashMap<(i64, i64), u64>, + second_path: &HashMap<(i64, i64), u64>, +) -> Result { + let first_path = first_path.keys().collect::>(); + let second_path = second_path.keys().collect::>(); + let cross_locations = first_path.intersection(&second_path); + + cross_locations + .map(|(x, y)| manhattan_distance((*x, *y), (0, 0))) + .min() + .ok_or_else(|| err!("the cables never crossed !")) +} + +fn part2( + first_path: &HashMap<(i64, i64), u64>, + second_path: &HashMap<(i64, i64), u64>, +) -> Result { first_path .keys() .filter(|pos| second_path.contains_key(&pos)) @@ -199,25 +161,33 @@ U98,R91,D20,R16,D67,R40,U7,R15,U6,R7 #[test] fn part1_provided() { - assert_eq!(part1(PROVIDED1).unwrap(), 6); - assert_eq!(part1(PROVIDED2).unwrap(), 159); - assert_eq!(part1(PROVIDED3).unwrap(), 135); + let (first, second) = parse_paths(PROVIDED1).unwrap(); + assert_eq!(part1(&first, &second).unwrap(), 6); + let (first, second) = parse_paths(PROVIDED2).unwrap(); + assert_eq!(part1(&first, &second).unwrap(), 159); + let (first, second) = parse_paths(PROVIDED3).unwrap(); + assert_eq!(part1(&first, &second).unwrap(), 135); } #[test] fn part1_real() { - assert_eq!(part1(INPUT).unwrap(), 273); + let (first, second) = parse_paths(INPUT).unwrap(); + assert_eq!(part1(&first, &second).unwrap(), 273); } #[test] fn part2_provided() { - assert_eq!(part2(PROVIDED1).unwrap(), 30); - assert_eq!(part2(PROVIDED2).unwrap(), 610); - assert_eq!(part2(PROVIDED3).unwrap(), 410); + let (first, second) = parse_paths(PROVIDED1).unwrap(); + assert_eq!(part2(&first, &second).unwrap(), 30); + let (first, second) = parse_paths(PROVIDED2).unwrap(); + assert_eq!(part2(&first, &second).unwrap(), 610); + let (first, second) = parse_paths(PROVIDED3).unwrap(); + assert_eq!(part2(&first, &second).unwrap(), 410); } #[test] fn part2_real() { - assert_eq!(part2(INPUT).unwrap(), 15622); + let (first, second) = parse_paths(INPUT).unwrap(); + assert_eq!(part2(&first, &second).unwrap(), 15622); } }