AoC 2027 Day 15 - rust

pareronia · pareronia · commit 3d8bcf302136 · 2025-01-09T21:17:10.000+01:00
diff --git a/README.md b/README.md
@@ -122,6 +122,7 @@
 | bash | [✓](src/main/bash/AoC2017_01.sh) | [✓](src/main/bash/AoC2017_02.sh) |  | [✓](src/main/bash/AoC2017_04.sh) | [✓](src/main/bash/AoC2017_05.sh) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 | c++ | [✓](src/main/cpp/2017/01/AoC2017_01.cpp) | [✓](src/main/cpp/2017/02/AoC2017_02.cpp) | [✓](src/main/cpp/2017/03/AoC2017_03.cpp) | [✓](src/main/cpp/2017/04/AoC2017_04.cpp) | [✓](src/main/cpp/2017/05/AoC2017_05.cpp) |  |  |  | [✓](src/main/cpp/2017/09/AoC2017_09.cpp) |  | [✓](src/main/cpp/2017/11/AoC2017_11.cpp) |  | [✓](src/main/cpp/2017/13/AoC2017_13.cpp) |  |  |  |  | [✓](src/main/cpp/2017/18/AoC2017_18.cpp) |  |  | [✓](src/main/cpp/2017/21/AoC2017_21.cpp) |  |  |  | [✓](src/main/cpp/2017/25/AoC2017_25.cpp) |
 | julia | [✓](src/main/julia/AoC2017_01.jl) | [✓](src/main/julia/AoC2017_02.jl) | [✓](src/main/julia/AoC2017_03.jl) | [✓](src/main/julia/AoC2017_04.jl) |  |  |  |  |  |  |  |  | [✓](src/main/julia/AoC2017_13.jl) |  |  |  |  |  |  |  |  |  |  |  |  |
+| rust |  |  |  |  |  |  |  |  |  |  |  |  |  |  | [✓](src/main/rust/AoC2017_15/src/main.rs) |  |  |  |  |  |  |  |  |  |  |
 <!-- @END:ImplementationsTable:2017@ -->
 
 ## 2016
diff --git a/src/main/rust/AoC2017_15/Cargo.toml b/src/main/rust/AoC2017_15/Cargo.toml
@@ -0,0 +1,7 @@
+[package]
+name = "AoC2017_15"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+aoc = { path = "../aoc" }
diff --git a/src/main/rust/AoC2017_15/src/main.rs b/src/main/rust/AoC2017_15/src/main.rs
@@ -0,0 +1,128 @@
+#![allow(non_snake_case)]
+
+use aoc::Puzzle;
+
+const FACTOR_A: u64 = 16807;
+const FACTOR_B: u64 = 48271;
+const MOD: u64 = 2147483647;
+
+enum Criteria {
+    A1,
+    B1,
+    A2,
+    B2,
+}
+
+impl Criteria {
+    fn apply(&self, val: u64) -> bool {
+        match self {
+            Self::A1 | Self::B1 => true,
+            Self::A2 => val % 4 == 0,
+            Self::B2 => val % 8 == 0,
+        }
+    }
+}
+
+struct Generator {
+    factor: u64,
+    val: u64,
+    criteria: Criteria,
+}
+
+impl Generator {
+    fn new(factor: u64, val: u64, criteria: Criteria) -> Self {
+        Self {
+            factor,
+            val,
+            criteria,
+        }
+    }
+}
+
+impl Iterator for Generator {
+    type Item = u64;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let mut nxt_val = self.val;
+        loop {
+            nxt_val = (nxt_val * self.factor) % MOD;
+            if self.criteria.apply(nxt_val) {
+                self.val = nxt_val;
+                return Some(nxt_val);
+            }
+        }
+    }
+}
+
+struct AoC2017_15;
+
+impl AoC2017_15 {
+    fn solve(
+        &self,
+        seeds: (u64, u64),
+        criteria: (Criteria, Criteria),
+        reps: usize,
+    ) -> usize {
+        let mut gen_a = Generator::new(FACTOR_A, seeds.0, criteria.0);
+        let mut gen_b = Generator::new(FACTOR_B, seeds.1, criteria.1);
+        (0..reps)
+            .filter(|_| {
+                gen_a.next().unwrap() & 0xFFFF == gen_b.next().unwrap() & 0xFFFF
+            })
+            .count()
+    }
+}
+
+impl aoc::Puzzle for AoC2017_15 {
+    type Input = (u64, u64);
+    type Output1 = usize;
+    type Output2 = usize;
+
+    aoc::puzzle_year_day!(2017, 15);
+
+    fn parse_input(&self, lines: Vec<String>) -> Self::Input {
+        let mut it = (0..=1).map(|i| {
+            lines[i]
+                .split_whitespace()
+                .last()
+                .unwrap()
+                .parse::<u64>()
+                .unwrap()
+        });
+        (it.next().unwrap(), it.next().unwrap())
+    }
+
+    fn part_1(&self, seeds: &Self::Input) -> Self::Output1 {
+        self.solve(*seeds, (Criteria::A1, Criteria::B1), 40_000_000)
+    }
+
+    fn part_2(&self, seeds: &Self::Input) -> Self::Output2 {
+        self.solve(*seeds, (Criteria::A2, Criteria::B2), 5_000_000)
+    }
+
+    fn samples(&self) {
+        aoc::puzzle_samples! {
+            self, part_1, TEST, 588,
+            self, part_2, TEST, 309
+        };
+    }
+}
+
+fn main() {
+    AoC2017_15 {}.run(std::env::args());
+}
+
+const TEST: &str = "\
+Generator A starts with 65
+Generator B starts with 8921
+";
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    pub fn samples() {
+        AoC2017_15 {}.samples();
+    }
+}
diff --git a/src/main/rust/Cargo.lock b/src/main/rust/Cargo.lock
