day16 part 1

2 files changed, 69 insertions, 0 deletions

diff --git a/src/day16.rs b/src/day16.rs
new file mode 100644
index 0000000..da1709c
--- /dev/null
+++ b/src/day16.rs
@@ -0,0 +1,67 @@
+use std::collections::HashMap;
+
+use regex::Regex;
+
+#[derive(Debug,Clone)]
+struct Track {
+    current_valve: String,
+    final_pressure_release: u32,
+    valves_opened: Vec<String>,
+    debug: String,
+}
+#[derive(Debug)]
+struct Valve {
+    flow_rate: u32,
+    next_valves: Vec<String>,
+}
+pub fn run(input: String) {
+    let re = Regex::new(r"^Valve ([A-Z]+) has flow rate=(\d+); tunnels? leads? to valves? ([A-Z, ]+)$").unwrap();
+    let valves: HashMap<String,Valve> = input.lines().map(|line| {
+        let cap = re.captures(line).expect(format!("line didn't match regex! {}", line).as_str());
+        let name = cap[1].to_string();
+        let flow_rate: u32 = cap[2].parse().expect("flow rate wasn't a u32!");
+        let next_valves: Vec<String> = cap[3].split(", ").map(|x| { x.to_string() }).collect();
+        (name, Valve{flow_rate,next_valves})
+    }).collect();
+    // How to do this one?
+    // I think... tracking all options? It's basically a tree right?
+    // max depth of the tree is 30,corresponding to minutes
+    // at each depth, options are -> open valve OR move to another valve
+    // and at each depth we have a score, and a list of already-opened valves 
+
+    let root = Track {current_valve: "AA".to_string(), final_pressure_release:0, valves_opened: vec![], debug: "Start at AA".to_string()};
+    let mut tracks: Vec<Track> = vec![root];
+    let mut next_tracks: Vec<Track> = Vec::new();
+    let total_mins: u32 = 30;
+    for minute in 0..=total_mins {
+        let mins_remaining = total_mins - minute;
+        for track in &tracks {
+            let cv = &valves[&track.current_valve];
+            // try open the valve (if it's got any flow, and if it's not already open)
+            if cv.flow_rate > 0 && !track.valves_opened.contains(&track.current_valve) {
+                let mut nt = track.clone();
+                nt.valves_opened.push(track.current_valve.clone());
+                if mins_remaining > 0 {
+                    nt.final_pressure_release += cv.flow_rate * (mins_remaining-1);
+                }
+                nt.debug.push_str(format!(", Opened {}", track.current_valve).as_str());
+                next_tracks.push(nt);
+            }
+            // Alt, try moving to another valve
+            for nv in &cv.next_valves {
+                let mut nt = track.clone();
+                nt.current_valve = nv.clone();
+                nt.debug.push_str(format!(", Moved to {}", nv).as_str());
+                next_tracks.push(nt);
+            }
+        }
+        next_tracks.sort_by(|t1, t2| {t1.final_pressure_release.cmp(&t2.final_pressure_release)}.reverse());
+        next_tracks.truncate(3_usize.pow(5));
+        tracks = next_tracks.clone();
+        next_tracks = Vec::new();// prune? keep the top N scorers?
+    }
+    // Find the track with the biggest final score
+    let max_track = tracks.iter().max_by(|t1,t2| {t1.final_pressure_release.cmp(&t2.final_pressure_release)}).unwrap();
+    //let max_pressure_release = tracks.iter().map(|t| {t.final_pressure_release}).max().unwrap();
+    println!("Day 16: {}", max_track.final_pressure_release);
+}
\ No newline at end of file
diff --git a/src/main.rs b/src/main.rs
index 9b0ea44..afee780 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -17,6 +17,7 @@ mod day12;
 mod day13;
 mod day14;
 mod day15;
+mod day16;
 
 fn main() {
     day1::run(fs::read_to_string("input/day1.txt").expect("Failed to read input file!"));
@@ -34,4 +35,5 @@ fn main() {
     day13::run(fs::read_to_string("input/day13.txt").expect("Failed to read input file!"));
     day14::run(fs::read_to_string("input/day14.txt").expect("Failed to read input file!"));
     day15::run(fs::read_to_string("input/day15.txt").expect("Failed to read input file!"));
+    day16::run(fs::read_to_string("input/day16.txt").expect("Failed to read input file!"));
 }