Complete part1 of day3

day3/src/main.rs

@@ -1,3 +1,77 @@
+fn get_rucksack_items(list: &str) -> (Vec<char>, Vec<char>) {
+    let all_chars: Vec<_> = list.chars().collect();
+
+    let half_index = all_chars.len() / 2;
+    let halves = all_chars.split_at(half_index);
+
+    assert_eq!(halves.0.len(), halves.1.len());
+
+    (halves.0.to_vec(), halves.1.to_vec())
+}
+
+fn get_priority(item: char) -> u32 {
+    let is_uppercase = item.is_ascii_uppercase();
+    let char = if is_uppercase {
+        item.to_ascii_lowercase()
+    } else {
+        item
+    };
+
+    let priority = match char {
+        'a' => 1,
+        'b' => 2,
+        'c' => 3,
+        'd' => 4,
+        'e' => 5,
+        'f' => 6,
+        'g' => 7,
+        'h' => 8,
+        'i' => 9,
+        'j' => 10,
+        'k' => 11,
+        'l' => 12,
+        'm' => 13,
+        'n' => 14,
+        'o' => 15,
+        'p' => 16,
+        'q' => 17,
+        'r' => 18,
+        's' => 19,
+        't' => 20,
+        'u' => 21,
+        'v' => 22,
+        'w' => 23,
+        'x' => 24,
+        'y' => 25,
+        'z' => 26,
+        _ => 0,
+    };
+
+    if is_uppercase {
+        priority + 26
+    } else {
+        priority
+    }
+}
+
+fn find_same_item(a: Vec<char>, b: Vec<char>) -> char {
+    for ch in a {
+        if b.contains(&ch) {
+            return ch;
+        }
+    }
+
+    panic!("We should have already found the item")
+}
+
 fn main() {
     let file_str = include_str!("input.txt");
+    let sum: u32 = file_str
+        .lines()
+        .map(|line| get_rucksack_items(line))
+        .map(|(a, b)| find_same_item(a, b))
+        .map(|item| get_priority(item))
+        .sum();
+
+    println!("Part 1 Priority Sum: {}", sum);
 }