day 08 solution

2023/Cargo.lock

@@ -2,6 +2,29 @@
 # It is not intended for manual editing.
 version = 3
 
+[[package]]
+name = "aho-corasick"
+version = "1.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b2969dcb958b36655471fc61f7e416fa76033bdd4bfed0678d8fee1e2d07a1f0"
+dependencies = [
+ "memchr",
+]
+
+[[package]]
+name = "aoc-parse"
+version = "0.2.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6b5d6981822b91def794ea9433e7547dc607e601dbd03b864dbe307a53af5798"
+dependencies = [
+ "lazy_static",
+ "num-bigint",
+ "num-traits",
+ "regex",
+ "thiserror",
+ "tuple_utils",
+]
+
 [[package]]
 name = "aoc-runner"
 version = "0.3.0"
@@ -35,16 +58,112 @@ dependencies = [
 name = "aoc2023"
 version = "0.1.0"
 dependencies = [
+ "aoc-parse",
  "aoc-runner",
  "aoc-runner-derive",
+ "num",
 ]
 
+[[package]]
+name = "autocfg"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d468802bab17cbc0cc575e9b053f41e72aa36bfa6b7f55e3529ffa43161b97fa"
+
 [[package]]
 name = "itoa"
 version = "1.0.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "af150ab688ff2122fcef229be89cb50dd66af9e01a4ff320cc137eecc9bacc38"
 
+[[package]]
+name = "lazy_static"
+version = "1.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e2abad23fbc42b3700f2f279844dc832adb2b2eb069b2df918f455c4e18cc646"
+
+[[package]]
+name = "memchr"
+version = "2.6.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f665ee40bc4a3c5590afb1e9677db74a508659dfd71e126420da8274909a0167"
+
+[[package]]
+name = "num"
+version = "0.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b05180d69e3da0e530ba2a1dae5110317e49e3b7f3d41be227dc5f92e49ee7af"
+dependencies = [
+ "num-bigint",
+ "num-complex",
+ "num-integer",
+ "num-iter",
+ "num-rational",
+ "num-traits",
+]
+
+[[package]]
+name = "num-bigint"
+version = "0.4.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "608e7659b5c3d7cba262d894801b9ec9d00de989e8a82bd4bef91d08da45cdc0"
+dependencies = [
+ "autocfg",
+ "num-integer",
+ "num-traits",
+]
+
+[[package]]
+name = "num-complex"
+version = "0.4.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1ba157ca0885411de85d6ca030ba7e2a83a28636056c7c699b07c8b6f7383214"
+dependencies = [
+ "num-traits",
+]
+
+[[package]]
+name = "num-integer"
+version = "0.1.45"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "225d3389fb3509a24c93f5c29eb6bde2586b98d9f016636dff58d7c6f7569cd9"
+dependencies = [
+ "autocfg",
+ "num-traits",
+]
+
+[[package]]
+name = "num-iter"
+version = "0.1.43"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7d03e6c028c5dc5cac6e2dec0efda81fc887605bb3d884578bb6d6bf7514e252"
+dependencies = [
+ "autocfg",
+ "num-integer",
+ "num-traits",
+]
+
+[[package]]
+name = "num-rational"
+version = "0.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0638a1c9d0a3c0914158145bc76cff373a75a627e6ecbfb71cbe6f453a5a19b0"
+dependencies = [
+ "autocfg",
+ "num-bigint",
+ "num-integer",
+ "num-traits",
+]
+
+[[package]]
+name = "num-traits"
+version = "0.2.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "39e3200413f237f41ab11ad6d161bc7239c84dcb631773ccd7de3dfe4b5c267c"
+dependencies = [
+ "autocfg",
+]
+
 [[package]]
 name = "proc-macro2"
 version = "1.0.70"
@@ -63,6 +182,35 @@ dependencies = [
  "proc-macro2",
 ]
 
+[[package]]
+name = "regex"
+version = "1.10.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "380b951a9c5e80ddfd6136919eef32310721aa4aacd4889a8d39124b026ab343"
+dependencies = [
+ "aho-corasick",
+ "memchr",
+ "regex-automata",
+ "regex-syntax",
+]
+
+[[package]]
+name = "regex-automata"
+version = "0.4.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5f804c7828047e88b2d32e2d7fe5a105da8ee3264f01902f796c8e067dc2483f"
+dependencies = [
+ "aho-corasick",
+ "memchr",
+ "regex-syntax",
+]
+
+[[package]]
+name = "regex-syntax"
+version = "0.8.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c08c74e62047bb2de4ff487b251e4a92e24f48745648451635cec7d591162d9f"
+
 [[package]]
 name = "ryu"
 version = "1.0.15"
@@ -122,6 +270,32 @@ dependencies = [
  "unicode-ident",
 ]
 
+[[package]]
+name = "thiserror"
+version = "1.0.50"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f9a7210f5c9a7156bb50aa36aed4c95afb51df0df00713949448cf9e97d382d2"
+dependencies = [
+ "thiserror-impl",
+]
+
+[[package]]
+name = "thiserror-impl"
+version = "1.0.50"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "266b2e40bc00e5a6c09c3584011e08b06f123c00362c92b975ba9843aaaa14b8"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.39",
+]
+
+[[package]]
+name = "tuple_utils"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cffaaf9392ef73cd30828797152476aaa2fa37a17856934fa63d4843f34290e9"
+
 [[package]]
 name = "unicode-ident"
 version = "1.0.12"

2023/Cargo.toml

@@ -10,3 +10,5 @@ path = "src/lib.rs"
 [dependencies]
 aoc-runner = "0.3.0"
 aoc-runner-derive = "0.3.0"
+aoc-parse = "0.2.17"
+num = "0.4"

2023/src/day01.rs

@@ -55,7 +55,6 @@ fn letter_digit_at(line: &str, index: usize) -> Option<u32> {
         let index2 = index + d.len();
         let substring: &str = line[index..index2].as_ref();
         if *d == substring {
-            // println!("compare {} dindex {} d {}", index, dindex, d);
             return Some(dindex as u32);
         }
     }
@@ -90,7 +89,6 @@ fn sub_letters_for_digits(input: &str) -> Vec<u32> {
                     }
                 }
                 let num = first_digit * 10 + second_digit;
-                println!("line {} num {}", line, num);
                 Some(num)
             } else {
                 None

2023/src/day02.rs

@@ -70,7 +70,7 @@ fn parse(input: &str) -> Vec<Game> {
                             "red" => red = count,
                             "green" => green = count,
                             "blue" => blue = count,
-                            _ => println!("invalid color! {}", dice_parts[0]),
+                            _ => panic!("invalid color! {}", dice_parts[0]),
                         }
                     }
                     turns.push(Turn { red, green, blue });

2023/src/day03.rs

@@ -84,7 +84,6 @@ fn associate_parts(input: &str) -> PartList {
             }
         }
     }
-    // println!("{:?}", result);
     result
 }
 

2023/src/day08.rs

@@ -0,0 +1,157 @@
+use aoc_runner_derive::aoc;
+use num::integer::lcm;
+use std::collections::{BTreeMap, HashSet};
+
+type NodePath<'a> = BTreeMap<&'a str, &'a str>;
+
+struct Path<'a> {
+    path: Vec<&'a str>,
+    left: NodePath<'a>,
+    right: NodePath<'a>,
+}
+
+fn parse(input: &str) -> Path {
+    let mut lines = input.lines();
+    let path = lines
+        .next()
+        .unwrap()
+        .split("")
+        .filter_map(|s| if s.is_empty() { None } else { Some(s) })
+        .collect::<Vec<&str>>();
+
+    let mut left: NodePath = BTreeMap::new();
+    let mut right: NodePath = BTreeMap::new();
+
+    for line in lines {
+        if line.is_empty() {
+            continue;
+        }
+        let parts1 = line.split(" = ").collect::<Vec<&str>>();
+        let src = parts1[0];
+        let parts2 = parts1[1]
+            .trim_start_matches("(")
+            .trim_end_matches(")")
+            .split(", ")
+            .collect::<Vec<&str>>();
+
+        left.insert(src, parts2[0]);
+        right.insert(src, parts2[1]);
+    }
+
+    Path { path, left, right }
+}
+
+impl<'a> Path<'a> {
+    fn traverse(&'a mut self) -> u64 {
+        let mut cur = "AAA";
+        let mut steps = 0;
+
+        for dir in self.path.iter().cycle() {
+            steps += 1;
+            match *dir {
+                "L" => cur = self.left.get(cur).unwrap(),
+                "R" => cur = self.right.get(cur).unwrap(),
+                n @ _ => panic!("Invalid character {:?}!", n),
+            }
+            if cur == "ZZZ" {
+                break;
+            }
+        }
+
+        steps
+    }
+
+    fn ghost_traverse(&'a mut self) -> u64 {
+        let mut unique: HashSet<&str> = HashSet::new();
+        for (src, _dest) in &self.left {
+            if src.ends_with("A") {
+                unique.insert(src);
+            }
+        }
+        for (src, _dest) in &self.right {
+            if src.ends_with("A") {
+                unique.insert(src);
+            }
+        }
+        let mut steps = 1;
+
+        for ghost in unique.into_iter() {
+            let mut gsteps = 0;
+            let mut cur = ghost;
+            for dir in self.path.iter().cycle() {
+                gsteps += 1;
+                match *dir {
+                    "L" => cur = self.left.get(cur).unwrap(),
+                    "R" => cur = self.right.get(cur).unwrap(),
+                    n @ _ => panic!("Invalid path character {:?}!", n),
+                }
+                if cur.ends_with("Z") {
+                    steps = lcm(gsteps, steps);
+                    break;
+                }
+            }
+        }
+
+        steps
+    }
+}
+
+#[aoc(day8, part1)]
+fn part1(input: &str) -> u64 {
+    parse(input).traverse()
+}
+
+#[aoc(day8, part2)]
+fn part2(input: &str) -> u64 {
+    parse(input).ghost_traverse()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const SAMPLE_DATA1: &'static str = r#"RL
+
+AAA = (BBB, CCC)
+BBB = (DDD, EEE)
+CCC = (ZZZ, GGG)
+DDD = (DDD, DDD)
+EEE = (EEE, EEE)
+GGG = (GGG, GGG)
+ZZZ = (ZZZ, ZZZ)
+"#;
+
+    #[test]
+    fn sample_data1() {
+        assert_eq!(part1(&SAMPLE_DATA1), 2);
+    }
+
+    const SAMPLE_DATA2: &'static str = r#"LLR
+
+AAA = (BBB, BBB)
+BBB = (AAA, ZZZ)
+ZZZ = (ZZZ, ZZZ)
+"#;
+
+    #[test]
+    fn sample_data2() {
+        assert_eq!(part1(&SAMPLE_DATA2), 6);
+    }
+
+    const SAMPLE_DATA_P2: &'static str = r#"LR
+
+11A = (11B, XXX)
+11B = (XXX, 11Z)
+11Z = (11B, XXX)
+22A = (22B, XXX)
+22B = (22C, 22C)
+22C = (22Z, 22Z)
+22Z = (22B, 22B)
+XXX = (XXX, XXX)
+"#;
+
+    #[test]
+    fn sample_data_part2() {
+        assert_eq!(part2(&SAMPLE_DATA_P2), 6);
+    }
+}

2023/src/lib.rs

@@ -7,5 +7,6 @@ mod day04;
 mod day05;
 mod day06;
 mod day07;
+mod day08;
 
 aoc_lib! { year = 2023 }