[rust] Solve Day 1

.gitignore

@@ -1,2 +1,3 @@
 .direnv
 dist-newstyle
+target

Cargo.lock

@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "aoc2023"
+version = "0.1.0"

Cargo.toml

@@ -0,0 +1,3 @@
+[workspace]
+members = ["rust"]
+resolver = "2"

README.org

@@ -24,3 +24,10 @@ Run it like this:
 ./bash/main.sh day<n> < ./input/day<n>
 #+END_SRC
 
+* Rust
+
+Run it like this:
+
+#+BEGIN_SRC bash
+cargo run -- day<n> < ./input/day<n>
+#+END_SRC

flake.nix

@@ -8,28 +8,8 @@
     flake-utils.lib.eachDefaultSystem (system:
       let
         pkgs = import nixpkgs { inherit system; };
-        # Avoids unnecessary recompiles
-        filteredSource = pkgs.lib.cleanSourceWith {
-          src = ./haskell;
-          filter = path: type:
-            let baseName = baseNameOf (toString path);
-            in pkgs.lib.cleanSourceFilter path type && !(
-              baseName == "flake.nix" ||
-              baseName == "flake.lock" ||
-              baseName == "dist-newstyle" ||
-              builtins.match "^cabal\.project\..*$" baseName != null ||
-              baseName == "hls.sh" ||
-              baseName == ".envrc" ||
-              baseName == "hie.yaml" ||
-              baseName == ".hlint.yaml" ||
-              baseName == ".hspec" ||
-              baseName == "ci"
-            );
-        };
         ghcOverrides = hself: hsuper: rec {
-          aoc2023 =  pkgs.haskell.lib.overrideSrc (hsuper.callPackage ./haskell/default.nix {}) {
-            src = filteredSource;
-          };
+          aoc2023 = hsuper.callPackage ./haskell/default.nix {};
         };
         ghc94Pkgs = pkgs.haskell.packages.ghc94.override {
           overrides = ghcOverrides;
@@ -44,12 +24,19 @@
               (pkgs.haskell-language-server.override {supportedGhcVersions = ["948"];})
               pkgs.cabal2nix
               pkgs.ormolu
+
               pkgs.shellcheck
+
+              pkgs.rustc
+              pkgs.cargo
+              pkgs.rustfmt
+              pkgs.rust-analyzer
+              pkgs.clippy
             ];
           };
           aoc2023-haskell = ghc94Pkgs.aoc2023;
           aoc2023-bash =
-            let bashDir = pkgs.runCommand "aoc2023-bash" {} ''
+            let bashDir = pkgs.runCommandLocal "aoc2023-bash" {} ''
               mkdir $out
               cp -r ${./bash} $out/bin
               chmod -R +w $out
@@ -62,24 +49,38 @@
                 ${bashDir}/bin/main.sh "''${@}"
               '';
             };
+          aoc2023-rust = pkgs.rustPlatform.buildRustPackage {
+            name = "aoc2023";
+            src = pkgs.lib.cleanSourceWith {
+              src = ./.;
+              filter = path: type:
+                let baseName = baseNameOf (toString path);
+                in pkgs.lib.cleanSourceFilter path type &&
+                  (pkgs.lib.strings.hasInfix "rust" path ||
+                  baseName == "Cargo.toml" ||
+                  baseName == "Cargo.lock");
+            };
+            cargoSha256 = "sha256-e27WE9K2yby+6vzu0cDojtG0+aTdED7vt7wFgEd2dAw=";
+          };
         };
         checks =
-          let mkCheck = (prefix: exec: day: parts: {
-                name = "${prefix}-${day}";
+          let mkCheck = (lang: exec: day: parts: {
+                name = "${lang}-${day}";
                 value = pkgs.testers.testEqualContents {
-                  assertion = day;
+                  assertion = "${lang}: ${day}";
                   expected = pkgs.writeText "expected" ''
                     Part 1 Answer: ${parts.part1}
                     Part 2 Answer: ${parts.part2}
                   '';
-                  actual = pkgs.runCommand "actual" {} ''
+                  actual = pkgs.runCommandLocal "actual" {} ''
                     "${exec}" "${day}" < "${./input}/${day}" >$out
                   '';
                 };
               });
 
           in pkgs.lib.attrsets.mapAttrs' (mkCheck "haskell" "${packages.aoc2023-haskell}/bin/aoc2023") answers
-          // pkgs.lib.attrsets.mapAttrs' (mkCheck "bash" "${packages.aoc2023-bash}/bin/aoc2023") answers;
+          // pkgs.lib.attrsets.mapAttrs' (mkCheck "bash" "${packages.aoc2023-bash}/bin/aoc2023") answers
+          // pkgs.lib.attrsets.mapAttrs' (mkCheck "rust" "${packages.aoc2023-rust}/bin/aoc2023") answers;
         defaultPackage = packages.dev-env;
       });
 }

rust/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "aoc2023"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

rust/src/day1.rs

@@ -0,0 +1,146 @@
+use std::io;
+use std::io::Read;
+use std::cmp::Ordering;
+
+pub fn run() {
+    let mut lines : Vec<u8> = Vec::new();
+    let read_result = io::stdin().read_to_end(&mut lines);
+    match read_result {
+        Err(e) => println!("Error while reading input: {}", e),
+        Ok(_) => {
+            match part1(lines.clone()) {
+                Some(s) => println!("Part 1 Answer: {}", s),
+                None => println!("Part 1 Answer: failed to compute")
+            };
+            match part2(lines) {
+                Some(s) => println!("Part 2 Answer: {}", s),
+                None => println!("Part 2 Answer: failed to compute")
+            }
+        }
+    }
+}
+
+fn part1(lines: Vec<u8>) -> Option<u32> {
+    general_solution(lines, first_digit, last_digit)
+}
+
+fn part2(lines: Vec<u8>) -> Option<u32> {
+    general_solution(lines, first_digit_with_creativity, last_digit_with_creativity)
+}
+
+fn general_solution(data: Vec<u8>, parse_tens: fn(&str) -> Option<u32>,parse_ones: fn(&str) -> Option<u32>) -> Option<u32> {
+    // Too hard to carry around the Result. Using `ok()` to convert it to
+    // `Option` doesn't work for some reason.
+    let text = String::from_utf8(data).unwrap();
+    let lines = text.lines();
+    let calibration_values : Option<Vec<u32>> =
+        lines.map(|line| {
+            let tens = parse_tens(line);
+            let ones = parse_ones(line);
+            tens.and_then(
+                |t| ones.and_then(
+                    |o| Some(t * 10 + o)
+                )
+            )
+        }).collect();
+    calibration_values.and_then(|x| Some(x.into_iter().sum()))
+}
+
+fn first_digit(s: &str) -> Option<u32> {
+    for c in s.chars() {
+        if c.is_digit(10) {
+            return c.to_digit(10);
+        }
+    }
+    None
+}
+
+fn last_digit(s: &str) -> Option<u32> {
+    for c in s.chars().rev() {
+        if c.is_digit(10) {
+            return c.to_digit(10);
+        }
+    }
+    None
+}
+
+struct SearchData {
+    value : u32,
+    position : Option<usize>,
+}
+
+fn lower_search_data(d1: &SearchData, d2: &SearchData) -> Ordering {
+    match (d1.position, d2.position) {
+        (None, None) => Ordering::Equal,
+        (Some(_), None) => Ordering::Less,
+        (None, Some(_)) => Ordering::Greater,
+        (Some(x), Some(y)) => x.cmp(&y)
+    }
+}
+
+fn greater_search_data(d1: &SearchData, d2: &SearchData) -> Ordering {
+    match (d1.position, d2.position) {
+        (None, None) => Ordering::Equal,
+        (Some(_), None) => Ordering::Greater,
+        (None, Some(_)) => Ordering::Less,
+        (Some(x), Some(y)) => x.cmp(&y)
+    }
+}
+
+fn first_digit_with_creativity(s: &str) -> Option<u32> {
+    let search_results = [ SearchData{ value: 0, position: s.find("0")},
+                           SearchData{ value: 1, position: s.find("1")},
+                           SearchData{ value: 2, position: s.find("2")},
+                           SearchData{ value: 3, position: s.find("3")},
+                           SearchData{ value: 4, position: s.find("4")},
+                           SearchData{ value: 5, position: s.find("5")},
+                           SearchData{ value: 6, position: s.find("6")},
+                           SearchData{ value: 7, position: s.find("7")},
+                           SearchData{ value: 8, position: s.find("8")},
+                           SearchData{ value: 9, position: s.find("9")},
+                           SearchData{ value: 0, position: s.find("zero")},
+                           SearchData{ value: 1, position: s.find("one")},
+                           SearchData{ value: 2, position: s.find("two")},
+                           SearchData{ value: 3, position: s.find("three")},
+                           SearchData{ value: 4, position: s.find("four")},
+                           SearchData{ value: 5, position: s.find("five")},
+                           SearchData{ value: 6, position: s.find("six")},
+                           SearchData{ value: 7, position: s.find("seven")},
+                           SearchData{ value: 8, position: s.find("eight")},
+                           SearchData{ value: 9, position: s.find("nine")}
+    ];
+
+    search_results
+        .into_iter()
+        .min_by(lower_search_data)
+        .and_then(|x| x.position.and_then(|_| Some(x.value)))
+}
+
+fn last_digit_with_creativity(s: &str) -> Option<u32> {
+    let search_results = [ SearchData{ value: 0, position: s.rfind("0")},
+                           SearchData{ value: 1, position: s.rfind("1")},
+                           SearchData{ value: 2, position: s.rfind("2")},
+                           SearchData{ value: 3, position: s.rfind("3")},
+                           SearchData{ value: 4, position: s.rfind("4")},
+                           SearchData{ value: 5, position: s.rfind("5")},
+                           SearchData{ value: 6, position: s.rfind("6")},
+                           SearchData{ value: 7, position: s.rfind("7")},
+                           SearchData{ value: 8, position: s.rfind("8")},
+                           SearchData{ value: 9, position: s.rfind("9")},
+                           SearchData{ value: 0, position: s.rfind("zero")},
+                           SearchData{ value: 1, position: s.rfind("one")},
+                           SearchData{ value: 2, position: s.rfind("two")},
+                           SearchData{ value: 3, position: s.rfind("three")},
+                           SearchData{ value: 4, position: s.rfind("four")},
+                           SearchData{ value: 5, position: s.rfind("five")},
+                           SearchData{ value: 6, position: s.rfind("six")},
+                           SearchData{ value: 7, position: s.rfind("seven")},
+                           SearchData{ value: 8, position: s.rfind("eight")},
+                           SearchData{ value: 9, position: s.rfind("nine")}
+    ];
+
+    search_results
+        .into_iter()
+        .max_by(greater_search_data)
+        .and_then(|x| x.position.and_then(|_| Some(x.value)))
+}

rust/src/main.rs

@@ -0,0 +1,16 @@
+use std::env;
+
+mod day1;
+
+fn main() {
+    let mut args = env::args();
+    let _prog_name = args.next();
+    let day = args.next();
+    match day {
+        Some(x) => match x.as_str() {
+            "day1" => day1::run(),
+            _ => todo!()
+        },
+        _ => println!("Please provide the day as day<n>"),
+    }
+}