Day 3, Part 1

2022/aoc2022/src/day3.rs

@@ -0,0 +1,60 @@
+use std::collections::HashSet;
+use std::collections::hash_set::{Intersection, IntoIter};
+use std::io::Result;
+use std::iter::Sum;
+
+use crate::file::line_reader_for_file;
+
+pub fn main(filename: &str) -> Result<()> {
+    let line_reader = line_reader_for_file(filename)?;
+
+    let mut priority_letters: Vec<char> = Vec::new();
+
+    for line in line_reader {
+        let line = line?;
+        assert!(line.len() % 2 == 0);
+
+        let compartment_size: usize = line.len() / 2;
+
+        let (left_compartment, right_compartment) = line.split_at(compartment_size);
+        let left_compartment_set: HashSet<char> = HashSet::from_iter(left_compartment.chars());
+        let right_compartment_set: HashSet<char> = HashSet::from_iter(right_compartment.chars());
+
+        let intersection = left_compartment_set.intersection(&right_compartment_set);
+        priority_letters.extend(intersection);
+    }
+
+    println!("{}", priority_letters
+        .iter()
+        .map(|c| String::from(*c))
+        .collect::<Vec<String>>()
+        .join(" "));
+
+    const LOWERCASE_A_SCORE: u32 = 'a' as u32;
+    const UPPERCASE_A_SCORE: u32 = 'A' as u32;
+
+    let scored_priority_letters: Vec<u32> =
+        priority_letters
+            .iter()
+            .map(|c| -> u32 {
+                let char_value: u32 = (*c).into();
+                if c.is_lowercase() {
+                    char_value - LOWERCASE_A_SCORE + 1
+                } else {
+                    char_value - UPPERCASE_A_SCORE + 27
+                }
+            })
+            .collect();
+
+    println!("{}", scored_priority_letters
+        .iter()
+        .map(|i| i.to_string())
+        .collect::<Vec<String>>()
+        .join(" "));
+
+    let sum_of_scored_priority_letters: u32 = scored_priority_letters
+        .iter().sum();
+    println!("Part 1: sum of scores of all priority items: {}", sum_of_scored_priority_letters);
+
+    Ok(())
+}

2022/aoc2022/src/main.rs

@@ -2,6 +2,7 @@ use std::env;
 
 mod day1;
 mod day2;
+mod day3;
 mod file;
 
 fn main() {
@@ -18,4 +19,9 @@ fn main() {
     let day2_datafile = &args[2];
     day2::main(day2_datafile.as_str())
         .expect("Unable to process day2 data file");
+
+    println!("----- Day 3 -----");
+    let day3_datafile = &args[3];
+    day3::main(day3_datafile.as_str())
+        .expect("Unable to process day3 data file");
 }