Simplified day6 :)
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933ff006d7
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176
src/day6.rs
176
src/day6.rs
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@ -1,160 +1,68 @@
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use std::collections::BTreeSet;
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use std::collections::HashMap;
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use std::iter::FromIterator;
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#[derive(Debug)]
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struct OrbitMap {
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ids: Vec<usize>,
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}
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impl OrbitMap {
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fn new(n: usize) -> Self {
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Self {
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ids: (0..n).collect::<Vec<usize>>(),
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}
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}
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fn orbit_around(&mut self, base: usize, orbiter: usize) {
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self.ids[orbiter] = base;
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//println!("{:?}", self.ids);
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}
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fn range(&self, idx: usize) -> usize {
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let mut i = idx;
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let mut cnt = 0;
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while i != self.ids[i] {
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cnt += 1;
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i = self.ids[i];
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}
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cnt
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}
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fn range_to(&self, idx: usize, limit: usize) -> usize {
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let mut i = idx;
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let mut cnt = 0;
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while i != limit {
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i = self.ids[i];
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cnt += 1;
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}
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cnt - 1
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}
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fn path(&self, idx: usize) -> BTreeSet<usize> {
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let mut i = idx;
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let mut res = BTreeSet::new();
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while i != self.ids[i] {
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res.insert(i);
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i = self.ids[i];
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}
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res
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}
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fn distance(&self, p: usize, q: usize) -> usize {
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let ppath = self.path(p);
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let qpath = self.path(q);
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let common_roots = ppath.intersection(&qpath);
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common_roots
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.map(|cr| self.range_to(p, *cr) + self.range_to(q, *cr))
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.min()
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.unwrap()
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}
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}
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fn get_pairs(input: &str) -> Vec<Vec<String>> {
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fn create_orbit_map(input: &str) -> HashMap<String, String> {
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let mut orbit_map: HashMap<String, String> = HashMap::new();
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input
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.lines()
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.map(|line| line.split(")").map(String::from).collect::<Vec<String>>())
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.collect()
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.map(|line| line.split(")").map(String::from).collect())
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.for_each(|pair: Vec<String>| {
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orbit_map.entry(pair[1].clone()).or_insert(pair[0].clone());
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});
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orbit_map
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}
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fn get_space_objects(input: &str) -> HashMap<String, usize> {
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let items = input
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.lines()
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.map(|line| line.split(")").map(String::from).collect::<Vec<String>>())
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.flatten();
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fn part1(input: &str) -> usize {
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let orbit_map = create_orbit_map(input);
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let mut space_objects: HashMap<String, usize> = HashMap::new();
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let mut n = 0;
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items.for_each(|x| {
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if !space_objects.contains_key(&x) {
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space_objects.insert(x, n);
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n += 1;
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let mut cnt: usize = 0;
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for obj in orbit_map.keys() {
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let mut key = obj;
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while let Some(val) = orbit_map.get(key) {
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cnt += 1;
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key = val;
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}
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});
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//println!("{:?}", space_objects);
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space_objects
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}
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cnt
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}
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fn calculate_map(input: &str) -> usize {
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let space_objects = get_space_objects(input);
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let pairs = get_pairs(input);
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let mut orbit_map = OrbitMap::new(space_objects.len());
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fn part2(input: &str) -> usize {
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let orbit_map = create_orbit_map(input);
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for pair in pairs {
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//println!("{:?}", pair);
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let base = space_objects.get(&pair[0]).unwrap();
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let orbiter = space_objects.get(&pair[1]).unwrap();
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orbit_map.orbit_around(*base, *orbiter);
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let my_traj: HashMap<String, usize> = HashMap::from_iter(
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std::iter::successors(orbit_map.get("YOU").map(|el| (el, 0)), |(nxt, n)| {
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(orbit_map.get(*nxt).map(|el| (el, n + 1 as usize)))
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})
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.map(|(el, n)| (String::from(el), n)),
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);
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let mut santa_transfers = 0;
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let mut santa = orbit_map.get("SAN").unwrap();
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loop {
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if my_traj.contains_key(santa) {
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return my_traj.get(santa).unwrap() + santa_transfers;
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} else {
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santa = orbit_map.get(santa).expect("no common orbits found");
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santa_transfers += 1;
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}
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}
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//println!("{:?}", orbit_map.ids);
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(0..orbit_map.ids.len()).map(|i| orbit_map.range(i)).sum()
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}
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fn calculate_distance(input: &str) -> usize {
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let space_objects = get_space_objects(input);
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let pairs = get_pairs(input);
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let mut orbit_map = OrbitMap::new(space_objects.len());
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for pair in pairs {
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//println!("{:?}", pair);
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let base = space_objects.get(&pair[0]).unwrap();
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let orbiter = space_objects.get(&pair[1]).unwrap();
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orbit_map.orbit_around(*base, *orbiter);
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}
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//println!("{:?}", orbit_map.ids);
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let me = *space_objects.get("YOU").unwrap();
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let santa = *space_objects.get("SAN").unwrap();
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orbit_map.distance(me, santa)
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}
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pub fn main() -> std::io::Result<()> {
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let input = std::include_str!("../day6-input.txt").trim();
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println!("part1 = {:?}", calculate_map(input));
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println!("part2 = {:?}", calculate_distance(input));
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println!("part1 = {:?}", part1(input));
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println!("part2 = {:?}", part2(input));
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Ok(())
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}
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#[test]
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fn test_day6_part1() {
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let input = "COM)B\n\
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B)C\n\
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C)D\n\
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D)E\n\
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E)F\n\
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B)G\n\
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G)H\n\
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D)I\n\
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E)J\n\
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J)K\n\
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K)L";
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assert_eq!(calculate_map(input), 42);
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let input = "COM)B\nB)C\nC)D\nD)E\nE)F\nB)G\nG)H\nD)I\nE)J\nJ)K\nK)L";
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assert_eq!(part1(input), 42);
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}
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#[test]
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fn test_day6_part2() {
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let input = "COM)B\n\
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B)C\n\
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C)D\n\
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D)E\n\
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E)F\n\
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B)G\n\
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G)H\n\
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D)I\n\
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E)J\n\
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J)K\n\
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K)L\n\
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K)YOU\n\
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I)SAN";
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assert_eq!(calculate_distance(input), 4);
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let input = "COM)B\nB)C\nC)D\nD)E\nE)F\nB)G\nG)H\nD)I\nE)J\nJ)K\nK)L\nK)YOU\nI)SAN";
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assert_eq!(part2(input), 4);
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}
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