day 6

src/aoc06/mod.rs

@@ -0,0 +1,50 @@
+use std::error::Error;
+use std::fs;
+use std::collections::HashMap;
+use std::str;
+
+
+pub fn both(filename: &str) -> Result<(), Box<dyn Error>> {
+    let contents = fs::read_to_string(filename)?;
+
+    let mut answers: HashMap<u8, bool> = HashMap::new();
+    let mut sum = 0;
+    for line in contents.lines() {
+        if line.trim() == "" {
+            sum += answers.len();
+            answers = HashMap::new();
+            continue
+        }
+
+        for byte in line.as_bytes() {
+            answers.insert(*byte, true);
+        }
+    }
+    sum += answers.len();
+    println!("sum of group unique questions with yes: {}", sum);
+    answers = HashMap::new();
+
+    let mut first = true;
+    sum = 0;
+    for line in contents.lines() {
+        if line.trim() == "" {
+            sum += answers.len();
+            answers = HashMap::new();
+            first = true;
+            continue
+        }
+        if first {
+            for byte in line.as_bytes() {
+                answers.insert(*byte, true);
+            }
+            first = false;
+        } else {
+            answers.retain(|k, _| line.as_bytes().contains(k));
+        }
+    }
+    sum += answers.len();
+    println!("sum of group questions with all yes: {}", sum);
+
+    Ok(())
+}
+

src/lib.rs

@@ -3,3 +3,4 @@ pub mod aoc02;
 pub mod aoc03;
 pub mod aoc04;
 pub mod aoc05;
+pub mod aoc06;

src/main.rs

@@ -12,6 +12,7 @@ fn main() {
         3 => advent_of_code::aoc03::both("./inputs/03-01.txt"),
         4 => advent_of_code::aoc04::both("./inputs/04-01.txt"),
         5 => advent_of_code::aoc05::both("./inputs/05-01.txt"),
+        6 => advent_of_code::aoc06::both("./inputs/06-01.txt"),
         _ => Err(format!("unsupported day {}", day).into()),
     };