Day 11 Done

Author: BakerNet

README.md

@@ -10,7 +10,7 @@ Solutions for [Advent of Code](https://adventofcode.com/) in [Rust](https://www.
 
 | Year | Completed |
 | :---: | :---: |
-| [2025](aoc2025) | 20/24 |
+| [2025](aoc2025) | 22/24 |
 | [2024](aoc2024) | 50/50 |
 | [2023](aoc2023) | 50/50 |
 | [2015](aoc2015) | 24/50 |

aoc2025/README.md

@@ -16,7 +16,7 @@ Solutions for [Advent of Code](https://adventofcode.com/) in [Rust](https://www.
 | [Day 8](https://adventofcode.com/2025/day/8) | [code](src/bin/08.rs) | ⭐ | ⭐ |
 | [Day 9](https://adventofcode.com/2025/day/9) | [code](src/bin/09.rs) | ⭐ | ⭐ |
 | [Day 10](https://adventofcode.com/2025/day/10) | [code](src/bin/10.rs) | ⭐ | ⭐ |
-| [Day 11](https://adventofcode.com/2025/day/11) | [code](src/bin/11.rs) | _ | _ |
+| [Day 11](https://adventofcode.com/2025/day/11) | [code](src/bin/11.rs) | ⭐ | ⭐ |
 | [Day 12](https://adventofcode.com/2025/day/12) | [code](src/bin/12.rs) | _ | _ |
 
 ---

aoc2025/data/examples/11-2.txt

@@ -0,0 +1,13 @@
+svr: aaa bbb
+aaa: fft
+fft: ccc
+bbb: tty
+tty: ccc
+ccc: ddd eee
+ddd: hub
+hub: fff
+eee: dac
+dac: fff
+fff: ggg hhh
+ggg: out
+hhh: out

aoc2025/data/examples/11.txt

@@ -0,0 +1,10 @@
+aaa: you hhh
+you: bbb ccc
+bbb: ddd eee
+ccc: ddd eee fff
+ddd: ggg
+eee: out
+fff: out
+ggg: out
+hhh: ccc fff iii
+iii: out

aoc2025/src/bin/11.rs

@@ -0,0 +1,123 @@
+use std::collections::HashMap;
+
+use itertools::Itertools;
+
+advent_of_code::solution!(11);
+
+fn parse_input(input: &str) -> (HashMap<usize, Vec<usize>>, HashMap<String, usize>) {
+    let mut machine_ids = HashMap::new();
+    let s_to_id = move |m: String, machine_ids: &mut HashMap<String, usize>| {
+        if let Some(x) = machine_ids.get(&m) {
+            *x
+        } else {
+            let curr = machine_ids.len();
+            machine_ids.insert(m, curr);
+            curr
+        }
+    };
+    let mut machines = HashMap::new();
+    input.lines().for_each(|s| {
+        let mut parts = s.split_whitespace();
+        let machine = parts
+            .next()
+            .expect("Should find machine")
+            .trim_end_matches(':')
+            .to_string();
+        let m = s_to_id(machine, &mut machine_ids);
+        let outputs = parts
+            .map(|x| s_to_id(x.to_string(), &mut machine_ids))
+            .collect_vec();
+        machines.insert(m, outputs);
+    });
+    (machines, machine_ids)
+}
+
+fn recurse_paths(
+    m: usize,
+    end: usize,
+    machines: &HashMap<usize, Vec<usize>>,
+    memo: &mut HashMap<usize, u64>,
+) -> u64 {
+    if m == end {
+        return 1;
+    }
+    if let Some(x) = memo.get(&m) {
+        return *x;
+    }
+    let mut total = 0;
+    for x in machines.get(&m).expect("All outputs should be inputs") {
+        total += recurse_paths(*x, end, machines, memo);
+    }
+    memo.insert(m, total);
+    total
+}
+
+pub fn part_one(input: &str) -> Option<u64> {
+    let (machines, machine_ids) = parse_input(input);
+    let start = machine_ids.get("you").unwrap();
+    let end = machine_ids.get("out").unwrap();
+    let mut seen = HashMap::new();
+    let total = recurse_paths(*start, *end, &machines, &mut seen);
+    Some(total)
+}
+
+fn recurse_paths_part2(
+    m: usize,
+    end: usize,
+    dac: usize,
+    fft: usize,
+    mut seen_dac: bool,
+    mut seen_fft: bool,
+    machines: &HashMap<usize, Vec<usize>>,
+    memo: &mut HashMap<(usize, bool, bool), u64>,
+) -> u64 {
+    if m == end {
+        return if seen_dac && seen_fft { 1 } else { 0 };
+    }
+    if m == dac {
+        seen_dac = true;
+    }
+    if m == fft {
+        seen_fft = true;
+    }
+    if let Some(x) = memo.get(&(m, seen_dac, seen_fft)) {
+        return *x;
+    }
+
+    let mut total = 0;
+    for x in machines.get(&m).expect("All outputs should be inputs") {
+        total += recurse_paths_part2(*x, end, dac, fft, seen_dac, seen_fft, machines, memo);
+    }
+    memo.insert((m, seen_dac, seen_fft), total);
+    total
+}
+
+pub fn part_two(input: &str) -> Option<u64> {
+    let (machines, machine_ids) = parse_input(input);
+    let start = machine_ids.get("svr").unwrap();
+    let end = machine_ids.get("out").unwrap();
+    let dac = machine_ids.get("dac").unwrap();
+    let fft = machine_ids.get("fft").unwrap();
+    let mut seen = HashMap::new();
+    let total = recurse_paths_part2(*start, *end, *dac, *fft, false, false, &machines, &mut seen);
+    Some(total)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_part_one() {
+        let result = part_one(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, Some(5));
+    }
+
+    #[test]
+    fn test_part_two() {
+        let result = part_two(&advent_of_code::template::read_file_part(
+            "examples", DAY, 2,
+        ));
+        assert_eq!(result, Some(2));
+    }
+}