day04

solved part 1 and 2 of day04

Author: sourproton

src/solutions/day04.rs

@@ -4,12 +4,124 @@
 //!
 //! https://adventofcode.com/2022/day/4
 
+use {
+    crate::helpers::{read_lines, Answer},
+    std::time::SystemTime,
+};
+
+/// solves the part 1 of day 04 and return its result and elapsed time
+pub fn pt1(filename: &str) -> Answer {
+    let time = SystemTime::now();
+
+    let answer = read_lines(filename)
+        .map(|line| parse_line(line).fully_contains())
+        .filter(|p| *p)
+        .count();
+
+    Answer::new(answer as u32, time.elapsed().unwrap().as_millis() as u32)
+}
+
+/// solves the part 2 of day 04 and return its result and elapsed time
+pub fn pt2(filename: &str) -> Answer {
+    let time = SystemTime::now();
+
+    let answer = read_lines(filename)
+        .map(|line| parse_line(line).contains())
+        .filter(|p| *p)
+        .count();
+
+    Answer::new(answer as u32, time.elapsed().unwrap().as_millis() as u32)
+}
+
+// parses a line into a SectionPair
+fn parse_line(line: String) -> SectionPair {
+    let splits: Vec<u32> = line
+        .replace(',', "-")
+        .split('-')
+        .map(|x| x.parse().unwrap())
+        .collect();
+
+    assert!(splits.len() == 4, "failed to parse line");
+
+    let first_section = Section::new(splits[0], splits[1]);
+    let second_section = Section::new(splits[2], splits[3]);
+
+    SectionPair::new(first_section, second_section)
+}
+
+/// represents a pair of `Section`s
+struct SectionPair {
+    first: Section,
+    second: Section,
+}
+
+impl SectionPair {
+    // determines if one section fully contains the other
+    fn fully_contains(&self) -> bool {
+        self.first.start <= self.second.start && self.first.end >= self.second.end
+            || self.first.start >= self.second.start && self.first.end <= self.second.end
+    }
+
+    // determines if one section contains the other
+    fn contains(&self) -> bool {
+        self.first.start <= self.second.end && self.first.end >= self.second.start
+            || self.second.start <= self.first.end && self.second.end >= self.first.start
+    }
+
+    // constructor
+    fn new(first: Section, second: Section) -> Self {
+        SectionPair { first, second }
+    }
+}
+
+/// represents the start and the end of the section the elf needs to clean
+struct Section {
+    start: u32,
+    end: u32,
+}
+
+impl Section {
+    // contructor
+    fn new(start: u32, end: u32) -> Self {
+        Section { start, end }
+    }
+}
+
 #[cfg(test)]
 mod tests {
-    use super::*;
+    use super::{parse_line, pt1, pt2};
+
+    const FILENAME: &str = "./data/examples/example04.txt";
+
+    #[test]
+    fn test_pt1() {
+        let answer = pt1(FILENAME);
+        assert_eq!(2, answer.answer());
+    }
+
+    #[test]
+    fn test_pt2() {
+        let answer = pt2(FILENAME);
+        assert_eq!(4, answer.answer());
+    }
+
+    #[test]
+    fn test_parse_line() {
+        let line = String::from("2-4,6-8");
+        let pair = parse_line(line);
+
+        assert_eq!(2, pair.first.start);
+        assert_eq!(4, pair.first.end);
+        assert_eq!(6, pair.second.start);
+        assert_eq!(8, pair.second.end);
+    }
 
-    // #[test]
-    // fn () {
+    #[test]
+    fn test_fully_contains() {
+        let pair1 = parse_line(String::from("2-4,6-8"));
+        let pair2 = parse_line(String::from("2-8,3-7"));
 
-    // }
+        assert!(!pair1.fully_contains());
+        assert!(pair2.fully_contains());
+    }
 }