add benchmarks for day 1

2020/01/src/main.rs

@@ -1,22 +1,54 @@
-#![feature(bool_to_option)]
+#![feature(test,bool_to_option)]
+extern crate test;
 use itertools::Itertools;
-use std::io::BufRead;
 
-fn main() {
-    let input: Vec<usize> = std::io::stdin().lock().lines().filter_map(|l| l.unwrap().parse().ok()).collect();
-    let p1 = input
+fn read_input() -> Vec<usize> {
+    std::fs::read_to_string("input")
+        .unwrap()
+        .lines()
+        .filter_map(|l| l.parse().ok())
+        .collect()
+}
+
+fn part1(input: &Vec<usize>) -> usize {
+    input
         .iter()
         .tuple_combinations()
         .find_map(|(&a, &b)| (a + b == 2020).then_some(a * b))
-        .unwrap();
-    println!("Part 1: {}", p1);
+        .unwrap()
+}
 
-    let mut p2_table = vec![None; 2020];
+fn part2(input: &Vec<usize>) -> usize {
+    let mut p2_table = [None; 2020];
     for (&a, &b) in input.iter().tuple_combinations() {
         if a + b < 2020 {
             p2_table[a + b] = Some((a, b))
         }
     }
     let (a, b) = input.iter().find_map(|x| p2_table[2020 - x]).unwrap();
-    println!("Part 2: {}", a * b * (2020 - a - b));
+    return a * b * (2020 - a - b);
+}
+
+fn main() {
+    let input = read_input();
+    println!("Part 1: {}", part1(&input));
+    println!("Part 2: {}", part2(&input));
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use test::{black_box, Bencher};
+
+    #[bench]
+    fn bench_part1(b: &mut Bencher) {
+        let input = read_input();
+        b.iter(|| black_box(part1(black_box(&input))));
+    }
+
+    #[bench]
+    fn bench_part2(b: &mut Bencher) {
+        let input = read_input();
+        b.iter(|| black_box(part2(black_box(&input))));
+    }
 }