day 4 solution

2022/src/days/day4.rs

@@ -0,0 +1,39 @@
+use anyhow::Result;
+use std::fs;
+
+pub fn run() -> Result<()> {
+    let file_contents = fs::read_to_string("day4.txt")?;
+    let lines = file_contents.lines();
+    let mut part_one_pairs = 0;
+    let mut part_two_pairs = 0;
+
+    for line in lines {
+        let v: Vec<&str> = line.split(",").collect();
+        let left: Vec<u32> = v[0].split("-").map(|t| t.parse::<u32>().unwrap()).collect();
+        let right: Vec<u32> = v[1].split("-").map(|t| t.parse::<u32>().unwrap()).collect();
+
+        let left_outside = left[0] <= right[0] && left[1] >= right[1];
+        let left_inside = left[0] >= right[0] && left[1] <= right[1];
+        let left_covered = left_outside || left_inside;
+
+        let right_outside = right[0] <= left[0] && right[1] >= left[1];
+        let right_inside = right[0] >= left[0] && right[1] <= left[1];
+        let right_covered = right_outside || right_inside;
+
+        if left_covered && right_covered {
+            part_one_pairs += 1;
+        }
+
+        let left_1_inside = left[0] >= right[0] && left[0] <= right[1];
+        let left_2_inside = left[1] >= right[0] && left[1] <= right[1];
+        let right_1_inside = right[0] >= left[0] && right[0] <= left[1];
+        let right_2_inside = right[1] >= left[0] && right[1] <= left[1];
+        if left_1_inside || left_2_inside || right_1_inside || right_2_inside {
+            part_two_pairs += 1;
+        }
+    }
+    println!("part one pairs {}", part_one_pairs);
+    println!("part two pairs {}", part_two_pairs);
+
+    Ok(())
+}

2022/src/days/mod.rs

@@ -1,3 +1,4 @@
 pub mod day1;
 pub mod day2;
 pub mod day3;
+pub mod day4;

2022/src/main.rs

@@ -14,10 +14,13 @@ fn run_day(number: i32) -> Result<()> {
         }
         2 => {
             days::day2::run()?;
-        },
+        }
         3 => {
             days::day3::run()?;
-        },
+        }
+        4 => {
+            days::day4::run()?;
+        }
         _ => return Err(anyhow!("Invalid day provided")),
     }
     Ok(())

2022/tests/day4.txt

@@ -0,0 +1,6 @@
+2-4,6-8
+2-3,4-5
+5-7,7-9
+2-8,3-7
+6-6,4-6
+2-6,4-8