My submissions for Advent of Code 2025
adventofcode.com/2025
cherry.computer
rust
aoc
add solution for day 11 part 2
+4
11/part2/Cargo.toml
+4
11/part2/Cargo.toml
+46
11/part2/src/main.rs
+46
11/part2/src/main.rs
···
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use std::{collections::HashMap, fs::read_to_string};
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fn traverse_map<'a>(
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device_map: &HashMap<&'a str, Vec<&'a str>>,
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seen_paths: &mut HashMap<&'a str, u64>,
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device: &'a str,
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target: &'a str,
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) -> u64 {
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match seen_paths.get(device) {
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Some(&known_path_count) => known_path_count,
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None => {
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let path_count = match &device_map.get(device) {
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Some(outputs) => outputs
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.iter()
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.map(|&output| {
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if output == target {
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1
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} else {
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traverse_map(device_map, seen_paths, output, target)
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}
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})
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.sum(),
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None => 0,
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};
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seen_paths.insert(device, path_count);
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path_count
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}
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}
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}
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fn main() {
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let input = read_to_string("../input.txt").expect("failed to open input file");
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let device_map: HashMap<_, Vec<_>> = input
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.lines()
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.map(|line| {
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let (device, outputs) = line.split_once(": ").expect("failed to parse line");
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(device, outputs.split_whitespace().collect())
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})
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.collect();
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let total_paths: u64 = [("svr", "fft"), ("fft", "dac"), ("dac", "out")]
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.into_iter()
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.map(|(from, to)| traverse_map(&device_map, &mut HashMap::new(), from, to))
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.product();
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println!("There are {total_paths} faulty paths from 'svr' to 'out'!");
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}