[rs] 2015:02: Solve day02

Author: kiriDevs

2015/day02/day02.rs

@@ -0,0 +1,78 @@
+use std::fs;
+use std::cmp::min;
+
+struct Gift { length: u64, width: u64, height: u64 }
+impl Gift {
+    /// Create a Gift object from a String
+    fn from_string(string: &String) -> Self {
+        let mut factors = string.trim().split("x").map(|num| {
+            num.parse::<u64>().unwrap()
+        });
+        let (length, width, height) = (
+            factors.next().unwrap(),
+            factors.next().unwrap(),
+            factors.next().unwrap()
+        );
+        if factors.next().is_some() {
+            panic!("Invalid gift specification");
+        }
+        Self { length, width, height }
+    }
+
+    /// The full surface area of the gift
+    fn area(&self) -> u64 {
+        (2 * self.length * self.width)
+        + (2 * self.width * self.height)
+        + (2 * self.length * self.height)
+    }
+
+    /// The overhead of packing paper used when packing the gift
+    fn packing_overhead(&self) -> u64 {
+        min(
+            min(self.length * self.width, self.width * self.height),
+            self.length * self.height
+        )
+    }
+
+    /// The volume of the box (for ribbon bows)
+    fn volume(&self) -> u64 {
+        self.length * self.width * self.height
+    }
+
+    /// Perimeter of the smallest side
+    fn perimeter(&self) -> u64 {
+        min(
+            min(
+                (2 * self.length) + (2 * self.width),
+                (2 * self.width) + (2 * self.height)
+            ),
+            (2 * self.length) + (2 * self.height)
+        )
+    }
+}
+
+fn read_input(filename: &str) -> Vec<String> {
+    if let Ok(input_text) = fs::read_to_string(filename) {
+        input_text
+            .trim()
+            .split("\n")
+            .map(|line| line.trim().to_owned())
+            .collect()
+    } else {
+        panic!("Unable to read input from file: {}", filename);
+    }
+}
+
+pub fn main() {
+    let gifts = read_input("day02.in").iter()
+        .map(Gift::from_string).collect::<Vec<Gift>>();
+
+    let solution1 = gifts.iter()
+        .map(|gift| gift.area() + gift.packing_overhead())
+        .fold(0, |accumulator, packing_paper| accumulator + packing_paper);
+    let solution2 = gifts.iter()
+        .map(|gift| gift.perimeter() + gift.volume())
+        .fold(0, |accumulator, ribbon| accumulator + ribbon);
+
+    println!("Part 1: {}\nPart 2: {}", solution1, solution2);
+}