1 files changed, 126 insertions, 0 deletions
diff --git a/2022/day4/src/lib.rs b/2022/day4/src/lib.rs
new file mode 100644
index 0000000..e64021b
--- /dev/null
+++ b/2022/day4/src/lib.rs
@@ -0,0 +1,126 @@
+use std::cmp::{max, min};
+use std::convert::From;
+
+#[derive(Debug)]
+struct Range {
+    start: i16,
+    end: i16,
+}
+
+#[derive(Debug)]
+struct Ranges {
+    one: Range,
+    two: Range,
+}
+
+impl From<&str> for Range {
+    fn from(item: &str) -> Self {
+        let dash_idx = item.find("-").expect("Can't find dash, can't parse.");
+        let start: i16 = item[..dash_idx].parse().unwrap();
+        let end: i16 = item[dash_idx + 1..].parse().unwrap();
+
+        Range { start, end }
+    }
+}
+
+impl From<&str> for Ranges {
+    fn from(item: &str) -> Self {
+        let comma_idx = item.find(",").expect("Comma not found, can't parse.");
+
+        Ranges {
+            one: item[..comma_idx].into(),
+            two: item[comma_idx + 1..].into(),
+        }
+    }
+}
+
+impl Ranges {
+    fn are_subset(&self) -> bool {
+        let a = &self.one;
+        let b = &self.two;
+
+        if a.start <= b.start && a.end >= b.end {
+            return true;
+        }
+
+        if b.start <= a.start && b.end >= a.end {
+            return true;
+        }
+
+        false
+    }
+
+    fn are_overlap(&self) -> bool {
+        let a = &self.one;
+        let b = &self.two;
+
+        return min(a.end, b.end) - max(a.start, b.start) >= 0;
+    }
+}
+
+pub fn part1(input: &str) -> u32 {
+    let ranges: Vec<Ranges> = input.trim().lines().map(|x| x.into()).collect();
+    let mut tot: u32 = 0;
+
+    for range in ranges {
+        if range.are_subset() {
+            tot += 1;
+        }
+    }
+
+    tot
+}
+
+pub fn part2(input: &str) -> u32 {
+    let ranges: Vec<Ranges> = input.trim().lines().map(|x| x.into()).collect();
+    let mut tot: u32 = 0;
+
+    for range in ranges {
+        if range.are_subset() || range.are_overlap() {
+            tot += 1;
+        }
+    }
+
+    tot
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_example() {
+        let data = include_str!("../example.txt");
+
+        let result = part1(data);
+
+        assert_eq!(result, 2);
+    }
+
+    #[test]
+    fn test_input1() {
+        let data = include_str!("../input.txt");
+
+        let result = part1(data);
+
+        assert_eq!(result, 595);
+    }
+
+    #[test]
+    fn test_example2() {
+        let data = include_str!("../example.txt");
+
+        let result = part2(data);
+
+        assert_eq!(result, 4);
+    }
+
+    #[test]
+    fn test_input2() {
+        let data = include_str!("../input.txt");
+
+        let result = part2(data);
+
+        assert_eq!(result, 952);
+    }
+}