2023 - Day 09

2023/src/bin/day09.rs

@@ -0,0 +1,129 @@
+#![feature(test)]
+#![feature(iter_map_windows)]
+use anyhow::Result;
+use aoc::Solver;
+
+// -- Runners --
+fn main() -> Result<()> {
+    Day::solve()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn part1_test1() -> Result<()> {
+        Day::test(Day::part1, "test-1", 114)
+    }
+
+    #[test]
+    fn part1_test2() -> Result<()> {
+        Day::test(Day::part1, "test-2", 18)
+    }
+
+    #[test]
+    fn part1_test3() -> Result<()> {
+        Day::test(Day::part1, "test-3", 28)
+    }
+
+    #[test]
+    fn part1_test4() -> Result<()> {
+        Day::test(Day::part1, "test-4", 68)
+    }
+
+    #[test]
+    fn part1_solution() -> Result<()> {
+        Day::test(Day::part1, "input", 1708206096)
+    }
+
+    #[test]
+    fn part2_test1() -> Result<()> {
+        Day::test(Day::part2, "test-1", 2)
+    }
+
+    #[test]
+    fn part2_test2() -> Result<()> {
+        Day::test(Day::part2, "test-2", -3)
+    }
+
+    #[test]
+    fn part2_test3() -> Result<()> {
+        Day::test(Day::part2, "test-3", 0)
+    }
+
+    #[test]
+    fn part2_test4() -> Result<()> {
+        Day::test(Day::part2, "test-4", 5)
+    }
+
+    #[test]
+    fn part2_solution() -> Result<()> {
+        Day::test(Day::part2, "input", 1050)
+    }
+
+    // Benchmarks
+    extern crate test;
+    #[bench]
+    #[ignore]
+    fn part1_bench(b: &mut test::Bencher) {
+        Day::benchmark(Day::part1, b)
+    }
+    #[bench]
+    #[ignore]
+    fn part2_bench(b: &mut test::Bencher) {
+        Day::benchmark(Day::part2, b)
+    }
+}
+
+// -- Solution --
+pub struct Day;
+impl aoc::Solver for Day {
+    type Output1 = isize;
+    type Output2 = isize;
+
+    fn day() -> u8 {
+        9
+    }
+
+    fn part1(input: &str) -> Self::Output1 {
+        input
+            .lines()
+            .map(|line| {
+                let mut nums: Vec<_> = line
+                    .split_whitespace()
+                    .map(|num| num.parse::<isize>().unwrap())
+                    .collect();
+
+                let mut next = *nums.last().unwrap();
+
+                while nums.iter().any(|&num| num != 0) {
+                    nums = nums.iter().map_windows(|[&a, &b]| b - a).collect();
+                    next += nums.last().unwrap();
+                }
+
+                next
+            })
+            .sum()
+    }
+
+    fn part2(input: &str) -> Self::Output2 {
+        input
+            .lines()
+            .map(|line| {
+                let mut nums: Vec<_> = line
+                    .split_whitespace()
+                    .map(|num| num.parse::<isize>().unwrap())
+                    .collect();
+
+                let mut firsts = vec![*nums.first().unwrap()];
+                while nums.iter().any(|&num| num != 0) {
+                    nums = nums.iter().map_windows(|[&a, &b]| b - a).collect();
+                    firsts.push(*nums.first().unwrap());
+                }
+
+                firsts.iter().rev().skip(1).fold(0, |diff, num| num - diff)
+            })
+            .sum()
+    }
+}