Added AOC 2020 day 21 - 25

www/statics/aoc/2020/21_solution.rs

@@ -0,0 +1,110 @@
+use crate::common::AdventOfCodeDay;
+
+use std::collections::HashMap;
+
+#[derive(Debug)]
+struct Food {
+    ingredients: Vec<String>,
+    allergens: Vec<String>,
+}
+
+impl Food {
+    fn parse(line: String) -> Food {
+        let split = line.split(" (contains ").collect::<Vec<_>>();
+
+        return Food {
+            ingredients: split[0].split(" ").map(String::from).collect(),
+            allergens: split[1].replace(")", "").split(", ").map(String::from).collect(),
+        }
+    }
+}
+
+#[derive(Debug)]
+pub struct Day21 {
+    input: Vec<Food>,
+}
+
+impl Day21 {
+    pub fn new() -> Self {
+        let input_bytes = include_bytes!("../res/21_input.txt");
+        let input_str = String::from_utf8_lossy(input_bytes);
+        
+        let data = input_str
+                        .lines()
+                        .map(|p| Food::parse(String::from(p)))
+                        .collect::<Vec<_>>();
+
+        Self {
+            input: data
+        }
+    }
+}
+
+impl Day21 {
+    fn find_allergen_candidates(&self) -> Vec<(String, Vec<String>)> {
+        let mut ag_map = HashMap::<String, Vec<String>>::new();
+
+        for food in &self.input {
+            for allergen in &food.allergens {
+
+                if let Some(candidates) = ag_map.get_mut(allergen) {
+
+                    candidates.retain(|c| food.ingredients.contains(c))
+
+                } else {
+                    ag_map.insert(allergen.clone(), food.ingredients.clone());
+                }
+            }
+        }
+
+        loop {
+            let mut changed = false;
+
+            for rm in ag_map.iter().filter(|(_,v)| v.len()==1).map(|(_,v)| v[0].clone()).collect::<Vec<_>>() {
+
+                for (_, cand_mut) in ag_map.iter_mut() {
+                    if cand_mut.len() == 1 { continue; }
+
+                    let l1 = cand_mut.len();
+                    cand_mut.retain(|v| *v != rm);
+                    if cand_mut.len() != l1 { changed = true; }
+                }
+
+            }
+
+            if !changed { break; }
+        }
+
+        return ag_map.iter().map(|(k,v)| (k.clone(), v.clone())).collect::<Vec<_>>();
+    }
+}
+
+impl AdventOfCodeDay for Day21 {
+
+    fn task_1(&self) -> String {
+
+        //for v in &self.input { verboseln!("{:?}", v); }
+
+        let candidates = self.find_allergen_candidates();
+
+        if is_verbose!() {
+            for (k,v) in &candidates { verboseln!("{: <9} ({}) := {:?}", k, v.len(), v); }
+        }
+
+        let allergen_ingred = candidates.iter().flat_map(|p| p.1.iter() ).collect::<Vec<_>>();
+
+        return self.input.iter().flat_map(|p| p.ingredients.iter()).filter(|ig| !allergen_ingred.contains(&ig)).count().to_string();
+    }
+
+    fn task_2(&self) -> String  {
+
+        let mut candidates = self.find_allergen_candidates();
+        candidates.sort_by(|a,b| a.0.cmp(&b.0));
+
+        if is_verbose!() {
+            for (k,v) in &candidates { verboseln!("{: <9} ({}) := {:?}", k, v.len(), v); }
+        }
+
+        return candidates.iter().map(|(_,v)|v[0].clone()).collect::<Vec<String>>().join(",");
+    }
+}