feat(02/2015): solve first part

Author: manhunto

readme.md

@@ -85,9 +85,10 @@
 
 # 2015
 
-| Day                                                      | Solved | Part 1 time (ms) | Part 2 time (ms) |
-|----------------------------------------------------------|:------:|-----------------:|-----------------:|
-| [Day 1: Not Quite Lisp](src/solutions/year2015/day01.rs) |   ⭐⭐   |            0.013 |            0.001 |
+| Day                                                                         | Solved | Part 1 time (ms) | Part 2 time (ms) |
+|-----------------------------------------------------------------------------|:------:|-----------------:|-----------------:|
+| [Day 1: Not Quite Lisp](src/solutions/year2015/day01.rs)                    |   ⭐⭐   |            0.013 |            0.001 |
+| [Day 2: I Was Told There Would Be No Math](src/solutions/year2015/day02.rs) |   ⭐    |            0.074 |                - |
 
 # TODO
 

src/solutions/mod.rs

@@ -86,6 +86,7 @@ pub fn solution(puzzle_day: PuzzleDay) -> Box<dyn Solution> {
         },
         Year::Year2015 => match i {
             1 => Box::new(year2015::day01::Day01),
+            2 => Box::new(year2015::day02::Day02),
             _ => panic!("Day not exist"),
         },
     }

src/solutions/year2015/day02.rs

@@ -0,0 +1,88 @@
+use crate::solutions::Solution;
+use itertools::Itertools;
+use std::str::FromStr;
+
+pub struct Day02;
+
+impl Solution for Day02 {
+    fn part_one(&self, input: &str) -> String {
+        self.parse(input)
+            .map(|cuboid| cuboid.surface_area() + cuboid.smallest_side_area())
+            .sum::<u64>()
+            .to_string()
+    }
+
+    fn part_two(&self, _input: &str) -> String {
+        String::from("0")
+    }
+}
+
+impl Day02 {
+    fn parse<'a>(&self, input: &'a str) -> impl Iterator<Item = RectangularCuboid> + 'a {
+        input.lines().map(|line| line.parse().unwrap())
+    }
+}
+
+struct RectangularCuboid {
+    width: u64,
+    length: u64,
+    height: u64,
+}
+
+impl RectangularCuboid {
+    fn surface_area(&self) -> u64 {
+        2 * self.area_width_length() + 2 * self.area_width_height() + 2 * self.area_length_height()
+    }
+
+    fn smallest_side_area(&self) -> u64 {
+        *[
+            self.area_width_length(),
+            self.area_width_height(),
+            self.area_length_height(),
+        ]
+        .iter()
+        .min()
+        .unwrap()
+    }
+
+    fn area_width_length(&self) -> u64 {
+        self.width * self.length
+    }
+
+    fn area_width_height(&self) -> u64 {
+        self.width * self.height
+    }
+
+    fn area_length_height(&self) -> u64 {
+        self.length * self.height
+    }
+}
+
+impl FromStr for RectangularCuboid {
+    type Err = String;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let (width, length, height) = s
+            .split_terminator('x')
+            .map(|s| s.parse::<u64>().unwrap())
+            .collect_tuple()
+            .unwrap();
+
+        Ok(Self {
+            width,
+            length,
+            height,
+        })
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn part_one_example_test() {
+        assert_eq!("58", Day02.part_one("2x3x4"));
+        assert_eq!("43", Day02.part_one("1x1x10"));
+    }
+}

src/solutions/year2015/mod.rs

@@ -1 +1,2 @@
 pub mod day01;
+pub mod day02;