Solve day 6

README.md

@@ -6,6 +6,19 @@ Solutions for [Advent of Code](https://adventofcode.com/) in [Rust](https://www.
 
 <!--- advent_readme_stars table --->
 
+<!--- benchmarking table --->
+## Benchmarks
+
+| Day | Part 1 | Part 2 |
+| :---: | :---: | :---:  |
+| [Day 1](./src/bin/01.rs) | `86.5µs` | `945.9µs` |
+| [Day 2](./src/bin/02.rs) | `48.9µs` | `61.7µs` |
+| [Day 3](./src/bin/03.rs) | `575.5µs` | `527.0µs` |
+| [Day 4](./src/bin/04.rs) | `295.7µs` | `274.8µs` |
+| [Day 5](./src/bin/05.rs) | `24.2µs` | `91.1µs` |
+| [Day 6](./src/bin/06.rs) | `410.0ns` | `5.4ms` |
+
+**Total: 8.33ms**
 <!--- benchmarking table --->
 
 ---

data/examples/06.txt

@@ -0,0 +1,2 @@
+Time:      7  15   30
+Distance:  9  40  200

src/bin/06.rs

@@ -0,0 +1,72 @@
+use itertools::Itertools;
+advent_of_code::solution!(6);
+
+fn line_as_numbers(line: &str) -> Vec<usize> {
+    line.split_once(": ")
+        .unwrap()
+        .1
+        .split(' ')
+        .filter(|time| !time.is_empty())
+        .map(|time| time.parse().unwrap())
+        .collect()
+}
+
+pub fn part_one(input: &str) -> Option<usize> {
+    let mut lines = input.lines();
+    let times = line_as_numbers(lines.next().unwrap());
+    let records = line_as_numbers(lines.next().unwrap());
+
+    Some(
+        times
+            .into_iter()
+            .zip_eq(records)
+            .map(|(time, record)| {
+                (1..time)
+                    .filter(|hold| (time - hold) * hold > record)
+                    .count()
+            })
+            .product(),
+    )
+}
+
+fn line_as_single_number(line: &str) -> usize {
+    line.split_once(": ")
+        .unwrap()
+        .1
+        .chars()
+        .filter(|char| *char != ' ')
+        .map(|time| time.to_digit(10).unwrap() as usize)
+        .collect::<Vec<usize>>()
+        .into_iter()
+        .rev()
+        .enumerate()
+        .map(|(index, value)| 10_usize.pow(index as u32) * value)
+        .sum()
+}
+
+pub fn part_two(input: &str) -> Option<usize> {
+    let mut lines = input.lines();
+    let time = line_as_single_number(lines.next().unwrap());
+    let record = line_as_single_number(lines.next().unwrap());
+
+    (1..time)
+        .find(|hold| (time - hold) * hold > record)
+        .map(|first| time - (2 * first) + 1)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_part_one() {
+        let result = part_one(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, Some(288));
+    }
+
+    #[test]
+    fn test_part_two() {
+        let result = part_two(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, Some(71503));
+    }
+}