From 6ec511998e5a9bda396d82bb544ad444bbc16723 Mon Sep 17 00:00:00 2001
From: pareronia <49491686+pareronia@users.noreply.github.com>
Date: Sat, 7 Dec 2024 20:49:28 +0100
Subject: [PATCH] AoC 2024 Day 7 - rust

---
 README.md                            |   2 +-
 src/main/rust/AoC2024_07/Cargo.toml  |   7 ++
 src/main/rust/AoC2024_07/src/main.rs | 128 +++++++++++++++++++++++++++
 src/main/rust/Cargo.lock             |   7 ++
 4 files changed, 143 insertions(+), 1 deletion(-)
 create mode 100644 src/main/rust/AoC2024_07/Cargo.toml
 create mode 100644 src/main/rust/AoC2024_07/src/main.rs

diff --git a/README.md b/README.md
index efb497fd..dfe39765 100644
--- a/README.md
+++ b/README.md
@@ -10,7 +10,7 @@
 | ---| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
 | python3 | [✓](src/main/python/AoC2024_01.py) | [✓](src/main/python/AoC2024_02.py) | [✓](src/main/python/AoC2024_03.py) | [✓](src/main/python/AoC2024_04.py) | [✓](src/main/python/AoC2024_05.py) | [✓](src/main/python/AoC2024_06.py) | [✓](src/main/python/AoC2024_07.py) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 | java | [✓](src/main/java/AoC2024_01.java) | [✓](src/main/java/AoC2024_02.java) | [✓](src/main/java/AoC2024_03.java) | [✓](src/main/java/AoC2024_04.java) | [✓](src/main/java/AoC2024_05.java) | [✓](src/main/java/AoC2024_06.java) | [✓](src/main/java/AoC2024_07.java) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
-| rust | [✓](src/main/rust/AoC2024_01/src/main.rs) | [✓](src/main/rust/AoC2024_02/src/main.rs) | [✓](src/main/rust/AoC2024_03/src/main.rs) | [✓](src/main/rust/AoC2024_04/src/main.rs) | [✓](src/main/rust/AoC2024_05/src/main.rs) | [✓](src/main/rust/AoC2024_06/src/main.rs) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
+| rust | [✓](src/main/rust/AoC2024_01/src/main.rs) | [✓](src/main/rust/AoC2024_02/src/main.rs) | [✓](src/main/rust/AoC2024_03/src/main.rs) | [✓](src/main/rust/AoC2024_04/src/main.rs) | [✓](src/main/rust/AoC2024_05/src/main.rs) | [✓](src/main/rust/AoC2024_06/src/main.rs) | [✓](src/main/rust/AoC2024_07/src/main.rs) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 <!-- @END:ImplementationsTable:2024@ -->
 
 ## 2023
diff --git a/src/main/rust/AoC2024_07/Cargo.toml b/src/main/rust/AoC2024_07/Cargo.toml
new file mode 100644
index 00000000..0b32259d
--- /dev/null
+++ b/src/main/rust/AoC2024_07/Cargo.toml
@@ -0,0 +1,7 @@
+[package]
+name = "AoC2024_07"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+aoc = { path = "../aoc" }
diff --git a/src/main/rust/AoC2024_07/src/main.rs b/src/main/rust/AoC2024_07/src/main.rs
new file mode 100644
index 00000000..197435fe
--- /dev/null
+++ b/src/main/rust/AoC2024_07/src/main.rs
@@ -0,0 +1,128 @@
+#![allow(non_snake_case)]
+
+use aoc::Puzzle;
+use std::collections::HashSet;
+
+#[derive(Eq, Hash, PartialEq)]
+enum Op {
+    Add,
+    Multiply,
+    Concatenate,
+}
+
+struct AoC2024_07;
+
+impl AoC2024_07 {
+    fn solve(
+        &self,
+        input: &<AoC2024_07 as aoc::Puzzle>::Input,
+        ops: &HashSet<Op>,
+    ) -> u64 {
+        fn can_obtain(sol: u64, terms: &[u64], ops: &HashSet<Op>) -> bool {
+            if terms.len() == 1 {
+                return sol == terms[0];
+            }
+            let last = terms.last().unwrap();
+            let prev_terms = &terms[..terms.len() - 1];
+            if ops.contains(&Op::Multiply)
+                && sol % last == 0
+                && can_obtain(sol.div_euclid(*last), prev_terms, ops)
+            {
+                return true;
+            }
+            if ops.contains(&Op::Add)
+                && sol > *last
+                && can_obtain(sol - *last, prev_terms, ops)
+            {
+                return true;
+            }
+            if ops.contains(&Op::Concatenate) {
+                let (s_sol, s_last) = (sol.to_string(), last.to_string());
+                if s_sol.len() > s_last.len() && s_sol.ends_with(&s_last) {
+                    let new_sol = &s_sol[..s_sol.len() - s_last.len()];
+                    if can_obtain(
+                        new_sol.parse::<u64>().unwrap(),
+                        prev_terms,
+                        ops,
+                    ) {
+                        return true;
+                    }
+                }
+            }
+            false
+        }
+
+        input
+            .iter()
+            .filter(|(sol, terms)| can_obtain(*sol, terms, ops))
+            .map(|(sol, _)| sol)
+            .sum()
+    }
+}
+
+impl aoc::Puzzle for AoC2024_07 {
+    type Input = Vec<(u64, Vec<u64>)>;
+    type Output1 = u64;
+    type Output2 = u64;
+
+    aoc::puzzle_year_day!(2024, 7);
+
+    fn parse_input(&self, lines: Vec<String>) -> Self::Input {
+        lines
+            .iter()
+            .map(|line| {
+                let (left, right) = line.split_once(": ").unwrap();
+                let sol = left.parse::<u64>().unwrap();
+                let terms = right
+                    .split_whitespace()
+                    .map(|s| s.parse::<u64>().unwrap())
+                    .collect();
+                (sol, terms)
+            })
+            .collect()
+    }
+
+    fn part_1(&self, input: &Self::Input) -> Self::Output1 {
+        self.solve(input, &HashSet::from([Op::Add, Op::Multiply]))
+    }
+
+    fn part_2(&self, input: &Self::Input) -> Self::Output2 {
+        self.solve(
+            input,
+            &HashSet::from([Op::Add, Op::Multiply, Op::Concatenate]),
+        )
+    }
+
+    fn samples(&self) {
+        aoc::puzzle_samples! {
+            self, part_1, TEST, 3749,
+            self, part_2, TEST, 11387
+        };
+    }
+}
+
+fn main() {
+    AoC2024_07 {}.run(std::env::args());
+}
+
+const TEST: &str = "\
+190: 10 19
+3267: 81 40 27
+83: 17 5
+156: 15 6
+7290: 6 8 6 15
+161011: 16 10 13
+192: 17 8 14
+21037: 9 7 18 13
+292: 11 6 16 20
+";
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    pub fn samples() {
+        AoC2024_07 {}.samples();
+    }
+}
diff --git a/src/main/rust/Cargo.lock b/src/main/rust/Cargo.lock
index 226a12c9..9013ad77 100644
--- a/src/main/rust/Cargo.lock
+++ b/src/main/rust/Cargo.lock
@@ -433,6 +433,13 @@ dependencies = [
  "indexmap",
 ]
 
+[[package]]
+name = "AoC2024_07"
+version = "0.1.0"
+dependencies = [
+ "aoc",
+]
+
 [[package]]
 name = "aho-corasick"
 version = "1.0.2"