Completed day 6

day06/Cargo.lock

@@ -0,0 +1,14 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+[[package]]
+name = "anyhow"
+version = "1.0.34"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bf8dcb5b4bbaa28653b647d8c77bd4ed40183b48882e130c1f1ffb73de069fd7"
+
+[[package]]
+name = "day06"
+version = "0.1.0"
+dependencies = [
+ "anyhow",
+]

day06/Cargo.toml

@@ -0,0 +1,10 @@
+[package]
+name = "day06"
+version = "0.1.0"
+authors = ["Tyler Hallada <tyler@hallada.net>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+anyhow = "1.0"

day06/input/test.txt

@@ -0,0 +1,15 @@
+abc
+
+a
+b
+c
+
+ab
+ac
+
+a
+a
+a
+a
+
+b

day06/src/main.rs

@@ -0,0 +1,66 @@
+use anyhow::Result;
+
+use std::collections::{HashMap, HashSet};
+use std::fs::read_to_string;
+
+const INPUT: &str = "input/input.txt";
+
+fn solve_part1(input_path: &str) -> Result<usize> {
+    let answers = read_to_string(input_path)?;
+    Ok(answers
+        .split("\n\n")
+        .map(|group| {
+            let mut answered = HashSet::new();
+            for person_answers in group.split("\n") {
+                for c in person_answers.chars() {
+                    answered.insert(c);
+                }
+            }
+            answered.len()
+        })
+        .sum())
+}
+
+fn solve_part2(input_path: &str) -> Result<usize> {
+    let answers = read_to_string(input_path)?;
+    Ok(answers
+        .split("\n\n")
+        .map(|group| {
+            let mut answer_counts = HashMap::new();
+            let mut group_len = 0;
+            for person_answers in group.trim().split("\n") {
+                for c in person_answers.chars() {
+                    let counter = answer_counts.entry(c).or_insert(0);
+                    *counter += 1;
+                }
+                group_len += 1;
+            }
+            answer_counts
+                .values()
+                .filter(|&&count| count == group_len)
+                .count()
+        })
+        .sum())
+}
+
+fn main() {
+    println!("Part 1: {}", solve_part1(INPUT).unwrap());
+    println!("Part 2: {}", solve_part2(INPUT).unwrap());
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const TEST_INPUT: &str = "input/test.txt";
+
+    #[test]
+    fn solves_part1() {
+        assert_eq!(solve_part1(TEST_INPUT).unwrap(), 11);
+    }
+
+    #[test]
+    fn solves_part2() {
+        assert_eq!(solve_part2(TEST_INPUT).unwrap(), 6);
+    }
+}