Add benchmark, clean up code

day-7/Cargo.toml

@@ -10,3 +10,7 @@ aoc-lib = { path = "../aoc-lib" }
 
 [dev-dependencies]
 criterion = "0.3"
+
+[[bench]]
+name = "bench"
+harness = false

day-7/benches/bench.rs

@@ -0,0 +1,46 @@
+#![allow(dead_code)]
+
+// uncomment for unstable version
+// #![allow(unused_attributes, incomplete_features)]
+// #![feature(generic_const_exprs, const_for, const_mut_refs)]
+
+use aoc_lib::AdventOfCode;
+use criterion::{black_box, criterion_group, criterion_main, Criterion};
+
+#[path = "../src/main.rs"]
+mod main;
+
+fn bench_main(c: &mut Criterion) {
+    c.bench_function("parse input", |b| {
+        let input = include_str!("../input.txt");
+        b.iter(|| main::Day7::parse_input(black_box(input)))
+    });
+
+    c.bench_function("solve 1", |b| {
+        let input = main::Day7::parse_input(include_str!("../input.txt"));
+        b.iter(|| main::Day7::solve_1(black_box(&input)))
+    });
+
+    c.bench_function("solve 2", |b| {
+        let input = main::Day7::parse_input(include_str!("../input.txt"));
+        b.iter(|| main::Day7::solve_2(black_box(&input)))
+    });
+
+    c.bench_function("parse sample input", |b| {
+        let input = include_str!("../sample.txt");
+        b.iter(|| main::Day7::parse_input(black_box(input)))
+    });
+
+    c.bench_function("solve 1 (sample input)", |b| {
+        let input = main::Day7::parse_input(include_str!("../sample.txt"));
+        b.iter(|| main::Day7::solve_1(black_box(&input)))
+    });
+
+    c.bench_function("solve 2 (sample input)", |b| {
+        let input = main::Day7::parse_input(include_str!("../sample.txt"));
+        b.iter(|| main::Day7::solve_2(black_box(&input)))
+    });
+}
+
+criterion_group!(benches, bench_main);
+criterion_main!(benches);

day-7/src/main.rs

@@ -17,16 +17,14 @@ impl AdventOfCode for Day7 {
         let min = *input.iter().min().unwrap();
         let max = *input.iter().max().unwrap();
 
-        let mut lowest_cost = usize::MAX;
-        for i in min..=max {
-            let cost = input
+        (min..=max).fold(usize::MAX, |acc, i| {
+            acc.min(
+                input
                     .iter()
-                .map(|&x| (x as isize - i as isize).abs() as usize)
-                .sum();
-            lowest_cost = lowest_cost.min(cost);
-        }
-
-        lowest_cost
+                    .map(|&x| ((x as isize - i as isize).abs() as usize))
+                    .sum(),
+            )
+        })
     }
 
     fn solve_2(input: &Self::Input) -> Self::Output {
@@ -34,19 +32,19 @@ impl AdventOfCode for Day7 {
         let min = *input.iter().min().unwrap();
         let max = *input.iter().max().unwrap();
 
-        let mut lowest_cost = usize::MAX;
-        for i in min..=max {
-            let cost = input
+        (min..=max).fold(usize::MAX, |acc, i| {
+            acc.min(
+                input
                     .iter()
                     .map(|&x| calculate_fuel((x as isize - i as isize).abs() as usize))
-                .sum();
-            lowest_cost = lowest_cost.min(cost);
-        }
-
-        lowest_cost
+                    .sum(),
+            )
+        })
     }
 }
 
 fn calculate_fuel(input: usize) -> usize {
+    // seems like rust is very smart: https://godbolt.org/z/WscWfvfdr
+    // TODO: figure out this algorithm and implement it myself
     (1..=input).sum()
 }