99 lines
2.4 KiB
Rust
99 lines
2.4 KiB
Rust
#![feature(test, map_first_last)]
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extern crate test;
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use itertools::Itertools;
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use std::{collections::BTreeSet, env};
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const NUM_ROWS: usize = 128;
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const NUM_COLS: usize = 8;
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#[derive(Debug, PartialEq)]
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struct Position {
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row: usize,
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col: usize,
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}
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#[inline]
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fn get_position(pass: &str) -> Position {
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Position {
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row: find_spot(&pass[0..7], 'B', NUM_ROWS),
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col: find_spot(&pass[7..], 'R', NUM_COLS),
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}
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}
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fn find_spot(s: &str, needle: char, max: usize) -> usize {
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s.chars()
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.zip(1..)
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.filter(|(c, _)| *c == needle)
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.fold(0, |acc, (_, n)| acc + (max >> n))
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}
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#[inline]
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fn calculate_id(p: &Position) -> usize {
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p.row * 8 + p.col
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}
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fn collect_ids(s: &str) -> BTreeSet<usize> {
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s.lines().map(get_position).map(|p| calculate_id(&p)).collect()
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}
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fn find_missing(ids: &BTreeSet<usize>) -> usize {
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ids.iter().tuple_windows().find(|(&a, &b)| b - a == 2).unwrap().0 + 1
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}
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fn main() {
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let ids = collect_ids(&read_input());
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let p1 = ids.last().unwrap();
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println!("Part 1: {}", p1);
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let p2 = find_missing(&ids);
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println!("Part 2: {}", p2);
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}
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fn read_input() -> String {
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std::fs::read_to_string(env::args().nth(1).filter(|n| n != "--bench").unwrap_or(String::from("inputs/day05"))).unwrap()
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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use test::black_box;
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const PASS_1: &str = "BFFFBBFRRR";
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const PASS_2: &str = "FFFBBBFRRR";
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const PASS_3: &str = "BBFFBBFRLL";
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const POS_1: Position = Position { row: 70, col: 7 };
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const POS_2: Position = Position { row: 14, col: 7 };
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const POS_3: Position = Position { row: 102, col: 4 };
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const SID_1: usize = 567;
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const SID_2: usize = 119;
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const SID_3: usize = 820;
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#[test]
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fn test_get_position() {
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assert_eq!(get_position(PASS_1), POS_1);
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assert_eq!(get_position(PASS_2), POS_2);
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assert_eq!(get_position(PASS_3), POS_3);
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}
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#[test]
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fn test_calculate_id() {
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assert_eq!(calculate_id(&POS_1), SID_1);
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assert_eq!(calculate_id(&POS_2), SID_2);
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assert_eq!(calculate_id(&POS_3), SID_3);
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}
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#[bench]
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fn bench_part_1(b: &mut test::Bencher) {
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let raw = read_input();
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b.iter(|| assert_eq!(collect_ids(black_box(&raw)).last(), Some(&913)))
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}
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#[bench]
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fn bench_part_2(b: &mut test::Bencher) {
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let ids = collect_ids(&read_input());
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b.iter(|| assert_eq!(find_missing(black_box(&ids)), 717))
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}
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}
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