Day 4

2018/src/day4.rs

@@ -0,0 +1,211 @@
+use std::collections::HashMap;
+
+extern crate regex;
+
+const INPUT: &str = include_str!("input/day4.txt");
+// const INPUT: &str = include_str!("input/day4_test.txt");
+
+#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Clone)]
+struct Timestamp {
+    date: String,
+    hour: u32,
+    minute: u32,
+}
+
+#[derive(Debug, PartialEq, Eq, PartialOrd, Ord)]
+enum Event {
+    WokeUp,
+    FellAsleep,
+    ShiftChange(String),
+}
+
+#[derive(Debug, PartialEq, Eq, PartialOrd, Ord)]
+struct Entry {
+    timestamp: Timestamp,
+    event: Event,
+}
+
+fn parse_input() -> Vec<Entry> {
+    let re: regex::Regex =
+        regex::Regex::new(r"^\[(\d{4}-\d{2}-\d{2}) (\d{2}):(\d{2})] (.*)$").unwrap();
+    let re_shift: regex::Regex = regex::Regex::new(r"^Guard #(\d+) begins shift$").unwrap();
+    let mut entries = Vec::new();
+    for line in str::lines(INPUT) {
+        let caps = re.captures(line).unwrap();
+        let date = caps.get(1).unwrap().as_str().to_string();
+        let hour = caps.get(2).unwrap().as_str().to_string().parse().unwrap();
+        let minute = caps.get(3).unwrap().as_str().to_string().parse().unwrap();
+        let ev = match caps.get(4).unwrap().as_str() {
+            "wakes up" => Event::WokeUp,
+            "falls asleep" => Event::FellAsleep,
+            shift => {
+                let caps = re_shift.captures(shift).unwrap();
+                Event::ShiftChange(caps.get(1).unwrap().as_str().to_string())
+            }
+        };
+        entries.push(Entry {
+            timestamp: Timestamp {
+                date: date,
+                hour: hour,
+                minute: minute,
+            },
+            event: ev,
+        });
+    }
+    entries
+}
+
+#[derive(Debug, Clone)]
+enum State {
+    Awake,
+    Asleep,
+}
+
+#[derive(Debug, Clone)]
+struct Minute {
+    timestamp: Timestamp,
+    guard: String,
+    state: State,
+}
+
+fn get_events(entries: &mut Vec<Entry>) -> Vec<Minute> {
+    entries.sort();
+    match entries[0].event {
+        Event::ShiftChange(_) => (),
+        _ => panic!("Invalid entry list!"),
+    }
+
+    let mut states = Vec::new();
+    let mut guard = "".to_string();
+    for e in entries {
+        let m = match &e.event {
+            Event::ShiftChange(g) => {
+                guard = g.to_string();
+                Minute {
+                    timestamp: e.timestamp.clone(),
+                    guard: guard.to_string(),
+                    state: State::Awake,
+                }
+            }
+            Event::FellAsleep => Minute {
+                timestamp: e.timestamp.clone(),
+                guard: guard.to_string(),
+                state: State::Asleep,
+            },
+            Event::WokeUp => Minute {
+                timestamp: e.timestamp.clone(),
+                guard: guard.to_string(),
+                state: State::Awake,
+            },
+        };
+        states.push(m);
+    }
+    states
+}
+
+fn sleep_intervals(ms: Vec<Minute>) -> Vec<((String, u32, u32))> {
+    let mut i = 0;
+    let mut ps = Vec::new();
+    while i + 1 < ms.len() {
+        let p1 = ms[i].clone();
+        let p2 = ms[i + 1].clone();
+        match (p1, p2) {
+            (
+                Minute {
+                    timestamp:
+                        Timestamp {
+                            date: _,
+                            hour: _,
+                            minute: m1,
+                        },
+                    guard: g1,
+                    state: State::Asleep,
+                },
+                Minute {
+                    timestamp:
+                        Timestamp {
+                            date: _,
+                            hour: _,
+                            minute: m2,
+                        },
+                    guard: g2,
+                    state: State::Awake,
+                },
+            ) => {
+                if g1 == g2 {
+                    ps.push((g1, m1, m2));
+                }
+            }
+            _ => {}
+        }
+        i += 1;
+    }
+    ps
+}
+
+fn mode(ms: Vec<u32>) -> u32 {
+    let mut buckets = HashMap::new();
+    for m in ms {
+        let mut b = buckets.entry(m).or_insert(0);
+        *b += 1;
+    }
+    let mut elts: Vec<(&u32, &u32)> = buckets.iter().collect();
+    elts.sort_by(|l, r| r.1.cmp(l.1));
+    *(elts[0].0)
+}
+
+fn interpolate_sleep(sleeps: Vec<(String, u32, u32)>) -> HashMap<String, Vec<u32>> {
+    let mut minutes_asleep: HashMap<String, Vec<u32>> = HashMap::new();
+    for (g, m1, m2) in sleeps {
+        let mut ms = minutes_asleep.entry(g).or_insert(Vec::new());
+        let mut m = m1;
+        while m < m2 {
+            ms.push(m);
+            m += 1;
+        }
+    }
+    minutes_asleep
+}
+
+fn sleep_data() -> HashMap<String, Vec<u32>> {
+    let mut input = parse_input();
+    let events = get_events(&mut input);
+    let sleeps = sleep_intervals(events);
+    let minutes_asleep = interpolate_sleep(sleeps);
+    minutes_asleep
+}
+
+pub fn part1() -> u32 {
+    let mut most_asleep = ("".to_string(), Vec::new());
+    for (g, ms) in sleep_data() {
+        if ms.len() > most_asleep.1.len() {
+            most_asleep = (g, ms);
+        }
+    }
+
+    let guard = most_asleep.0.parse::<u32>().unwrap();
+    let minute = mode(most_asleep.1);
+    minute * guard
+}
+
+fn mode2(ms: Vec<(u32, u32)>) -> (u32, u32) {
+    let mut buckets = HashMap::new();
+    for m in ms {
+        let mut b = buckets.entry(m).or_insert(0);
+        *b += 1;
+    }
+    let mut elts: Vec<(&(u32, u32), &u32)> = buckets.iter().collect();
+    elts.sort_by(|l, r| r.1.cmp(l.1));
+    *(elts[0].0)
+}
+
+pub fn part2() -> u32 {
+    let mut points: Vec<(u32, u32)> = Vec::new();
+    for (g, ms) in sleep_data() {
+        for m in ms {
+            points.push((g.parse::<u32>().unwrap(), m.clone()));
+        }
+    }
+    let (g, m) = mode2(points);
+    g * m
+}

2018/src/main.rs

@@ -1,6 +1,7 @@
 mod day1;
 mod day2;
 mod day3;
+mod day4;
 
 fn main() {
     println!("Day 1 part 1: {}", day1::part1());
@@ -9,4 +10,6 @@ fn main() {
     println!("Day 2 part 2: {}", day2::part2());
     println!("Day 3 part 1: {}", day3::part1());
     println!("Day 3 part 2: {}", day3::part2());
+    println!("Day 4 part 1: {}", day4::part1());
+    println!("Day 4 part 2: {}", day4::part2());
 }