5 files changed, 137 insertions(+), 1 deletions(-)

M Cargo.lock
M Cargo.toml
A day_06/Cargo.toml
A day_06/src/group.rs
A day_06/src/main.rs

@@ 38,3 38,10 @@ version = "1.0.0"
 dependencies = [
  "common",
 ]
+
+[[package]]
+name = "day_06"
+version = "1.0.0"
+dependencies = [
+ "common",
+]

@@ 5,7 5,8 @@ members = [
     "day_02",
     "day_03",
     "day_04",
-    "day_05"
+    "day_05",
+    "day_06"
 ]
 
 [profile.release]

@@ 0,0 1,12 @@
+[package]
+name = "day_06"
+version = "1.0.0"
+description = "Day 6 - Advent of Code 2020"
+authors = ["Jan Baudisch <jan@baudisch.xyz>"]
+license = "GPL-3.0-or-later"
+readme = "../README.md"
+edition = "2018"
+workspace = ".."
+
+[dependencies]
+common = { path = "../common" }

@@ 0,0 1,50 @@
+pub struct Group(Vec<Vec<char>>);
+
+impl From<&Vec<String>> for Group {
+    fn from(input: &Vec<String>) -> Self {
+        let mut persons = Vec::with_capacity(input.len());
+
+        for person in input {
+            persons.push(person.chars().collect());
+        }
+
+        Self(persons)
+    }
+}
+
+impl From<Vec<String>> for Group {
+    fn from(input: Vec<String>) -> Self {
+        Group::from(&input)
+    }
+}
+
+impl Group {
+    pub fn count_anyone_yes(&self) -> usize {
+        let mut combined = self.0.concat();
+        combined.sort_unstable();
+        combined.dedup();
+        combined.len()
+    }
+
+    pub fn count_everyone_yes(&self) -> usize {
+        let first = &self.0[0];
+
+        if self.0.len() == 1 {
+            return first.len();
+        }
+
+        let mut count = 0;
+
+        'answers: for answer in first {
+            for other in self.0.iter() {
+                if !other.contains(answer) {
+                    continue 'answers;
+                }
+            }
+
+            count += 1;
+        }
+
+        count
+    }
+}

@@ 0,0 1,66 @@
+mod group;
+
+use common::input;
+use group::Group;
+
+fn main() {
+    let groups: Vec<Group> = input::read_blocks().iter().map(|x| x.into()).collect();
+
+    let count: u32 = groups.iter().map(|x| x.count_anyone_yes() as u32).sum();
+
+    println!("[PART ONE] sum of \"yes\" answeres from anyone: {}", count);
+
+    let count: u32 = groups.iter().map(|x| x.count_everyone_yes() as u32).sum();
+
+    println!(
+        "[PART TWO] sum of \"yes\" answeres from everyone: {}",
+        count
+    );
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Group;
+
+    fn generate_groups() -> Vec<Group> {
+        let input = vec![
+            vec!["abc"],
+            vec!["a", "b", "c"],
+            vec!["ab", "ac"],
+            vec!["a", "a", "a", "a"],
+            vec!["b"],
+        ];
+
+        input
+            .into_iter()
+            .map(|x| {
+                x.into_iter()
+                    .map(|x| x.to_string())
+                    .collect::<Vec<String>>()
+            })
+            .map(|x| x.into())
+            .collect()
+    }
+
+    #[test]
+    fn part_one() {
+        assert_eq!(
+            generate_groups()
+                .iter()
+                .map(|x| x.count_anyone_yes() as u32)
+                .sum::<u32>(),
+            11
+        );
+    }
+
+    #[test]
+    fn part_two() {
+        assert_eq!(
+            generate_groups()
+                .iter()
+                .map(|x| x.count_everyone_yes() as u32)
+                .sum::<u32>(),
+            6
+        );
+    }
+}