complete day 3

src/day_3.rs

@@ -0,0 +1,33 @@
+
+pub fn part_1(input: &str) -> u64 {
+    let mut priorities_sum: u64 = 0;
+    let backpacks = input.lines();
+
+    for backpack in backpacks {
+        // todo this should be .chars() or something
+        let items: Vec<&str> = backpack.split("").collect();
+        let items_per_compartment = items.len() / 2;
+        let first_compartment = &items[1..items_per_compartment];
+        let second_compartment= &items[items_per_compartment..(items.len() - 1)];
+
+        for item in first_compartment {
+            if second_compartment.contains(item) {
+                let mut byte = item.as_bytes()[0] as u64;
+
+                // this is kind of diabolical
+                if item.to_string() == item.to_uppercase() {
+                    // reduce by some lesser amount?
+                    byte -= 38;
+                } else {
+                    byte -= 96;
+                }
+
+                priorities_sum += byte;
+
+                break;
+            }
+        }
+    }
+
+    priorities_sum
+}

src/main.rs

@@ -1,9 +1,11 @@
 mod day_1;
 mod day_2;
+mod day_3;
 
 fn main() {
     println!("Day 1, part 1: {}", day_1::part_1(include_str!("../input/day_1.txt")));
     println!("Day 1, part 2: {}", day_1::part_2(include_str!("../input/day_1.txt")));
     println!("Day 2, part 1: {}", day_2::part_1(include_str!("../input/day_2.txt")));
     println!("Day 2, part 2: {}", day_2::part_2(include_str!("../input/day_2.txt")));
+    println!("Day 3, part 1: {}", day_3::part_1(include_str!("../input/day_3.txt")));
 }