y2015d13

y2015/resources/13_input.txt

@@ -0,0 +1,56 @@
+Alice would gain 54 happiness units by sitting next to Bob.
+Alice would lose 81 happiness units by sitting next to Carol.
+Alice would lose 42 happiness units by sitting next to David.
+Alice would gain 89 happiness units by sitting next to Eric.
+Alice would lose 89 happiness units by sitting next to Frank.
+Alice would gain 97 happiness units by sitting next to George.
+Alice would lose 94 happiness units by sitting next to Mallory.
+Bob would gain 3 happiness units by sitting next to Alice.
+Bob would lose 70 happiness units by sitting next to Carol.
+Bob would lose 31 happiness units by sitting next to David.
+Bob would gain 72 happiness units by sitting next to Eric.
+Bob would lose 25 happiness units by sitting next to Frank.
+Bob would lose 95 happiness units by sitting next to George.
+Bob would gain 11 happiness units by sitting next to Mallory.
+Carol would lose 83 happiness units by sitting next to Alice.
+Carol would gain 8 happiness units by sitting next to Bob.
+Carol would gain 35 happiness units by sitting next to David.
+Carol would gain 10 happiness units by sitting next to Eric.
+Carol would gain 61 happiness units by sitting next to Frank.
+Carol would gain 10 happiness units by sitting next to George.
+Carol would gain 29 happiness units by sitting next to Mallory.
+David would gain 67 happiness units by sitting next to Alice.
+David would gain 25 happiness units by sitting next to Bob.
+David would gain 48 happiness units by sitting next to Carol.
+David would lose 65 happiness units by sitting next to Eric.
+David would gain 8 happiness units by sitting next to Frank.
+David would gain 84 happiness units by sitting next to George.
+David would gain 9 happiness units by sitting next to Mallory.
+Eric would lose 51 happiness units by sitting next to Alice.
+Eric would lose 39 happiness units by sitting next to Bob.
+Eric would gain 84 happiness units by sitting next to Carol.
+Eric would lose 98 happiness units by sitting next to David.
+Eric would lose 20 happiness units by sitting next to Frank.
+Eric would lose 6 happiness units by sitting next to George.
+Eric would gain 60 happiness units by sitting next to Mallory.
+Frank would gain 51 happiness units by sitting next to Alice.
+Frank would gain 79 happiness units by sitting next to Bob.
+Frank would gain 88 happiness units by sitting next to Carol.
+Frank would gain 33 happiness units by sitting next to David.
+Frank would gain 43 happiness units by sitting next to Eric.
+Frank would gain 77 happiness units by sitting next to George.
+Frank would lose 3 happiness units by sitting next to Mallory.
+George would lose 14 happiness units by sitting next to Alice.
+George would lose 12 happiness units by sitting next to Bob.
+George would lose 52 happiness units by sitting next to Carol.
+George would gain 14 happiness units by sitting next to David.
+George would lose 62 happiness units by sitting next to Eric.
+George would lose 18 happiness units by sitting next to Frank.
+George would lose 17 happiness units by sitting next to Mallory.
+Mallory would lose 36 happiness units by sitting next to Alice.
+Mallory would gain 76 happiness units by sitting next to Bob.
+Mallory would lose 34 happiness units by sitting next to Carol.
+Mallory would gain 37 happiness units by sitting next to David.
+Mallory would gain 40 happiness units by sitting next to Eric.
+Mallory would gain 18 happiness units by sitting next to Frank.
+Mallory would gain 7 happiness units by sitting next to George.

y2015/src/bin/d13.rs

@@ -0,0 +1,20 @@
+use std::fs;
+
+use y2015::days::d13;
+
+fn main() {
+    part1();
+    part2();
+}
+
+fn part1() {
+    let root = env!("CARGO_MANIFEST_DIR");
+    let content = fs::read_to_string(format!("{root}/resources/13_input.txt")).unwrap();
+    println!("{}", d13::process_part1(&content));
+}
+
+fn part2() {
+    let root = env!("CARGO_MANIFEST_DIR");
+    let content = fs::read_to_string(format!("{root}/resources/13_input.txt")).unwrap();
+    println!("{}", d13::process_part2(&content));
+}

y2015/src/days/d13.rs

@@ -0,0 +1,183 @@
+use core::panic;
+use std::{collections::HashMap, error::Error};
+
+pub fn process_part1(input: &str) -> i32 {
+    let mut happiness_table = HashMap::new();
+    let mut people = Vec::new();
+    input.lines().for_each(|line| {
+        let words = line.split_whitespace().collect::<Vec<&str>>();
+        let happiness = match words[2] {
+            "gain" => words[3].parse::<i32>().expect("Should be number"),
+            "lose" => -words[3].parse::<i32>().expect("Should be number"),
+            _ => panic!("Should not happen"),
+        };
+        let person = words[0].to_string();
+        let mut next_to = words[10].to_string();
+        next_to.pop();
+        if !people.contains(&person) {
+            people.push(person.clone());
+        }
+        happiness_table.insert((person, next_to), happiness);
+    });
+
+    let num_people = people.len();
+
+    let possible_permutations = factorial(num_people);
+
+    let mut highest_happiness = 0;
+    for idx in 1..possible_permutations {
+        let mut happiness = 0;
+        let permutation = permutation(people.clone(), idx).unwrap();
+
+        for (pos, person) in permutation.clone().iter().enumerate() {
+            let left_neighbor = {
+                if pos == 0 {
+                    permutation[num_people - 1].clone()
+                } else {
+                    permutation[pos - 1].clone()
+                }
+            };
+            let right_neighbor = {
+                if pos == num_people - 1 {
+                    permutation[0].clone()
+                } else {
+                    permutation[pos + 1].clone()
+                }
+            };
+
+            let left_happiness = happiness_table
+                .get(&(person.to_owned(), left_neighbor))
+                .unwrap();
+            let right_happiness = happiness_table
+                .get(&(person.to_owned(), right_neighbor))
+                .unwrap();
+            happiness += left_happiness + right_happiness;
+        }
+
+        if happiness > highest_happiness {
+            highest_happiness = happiness;
+        }
+    }
+
+    highest_happiness
+}
+
+fn permutation(mut people: Vec<String>, nth: usize) -> Result<Vec<String>, Box<dyn Error>> {
+    people.sort();
+    if nth == 1 {
+        return Ok(people);
+    }
+    if nth > factorial(people.len()) || nth == 0 {
+        return Err(Box::from("Out of bounds"));
+    }
+    let mut perm = Vec::new();
+    let num_unique_locations = people.len();
+    let mut remainder = nth - 1;
+    for idx in 1..=people.len() {
+        let permutations = remainder / factorial(num_unique_locations - idx);
+        remainder %= factorial(num_unique_locations - idx);
+        perm.push(people[permutations].clone());
+        people.remove(permutations);
+    }
+    Ok(perm)
+}
+
+fn factorial(num: usize) -> usize {
+    let mut fact = 1;
+    for n in 1..=num {
+        fact *= n;
+    }
+    fact
+}
+
+pub fn process_part2(input: &str) -> i32 {
+    let mut happiness_table = HashMap::new();
+    let mut people = Vec::new();
+    input.lines().for_each(|line| {
+        let words = line.split_whitespace().collect::<Vec<&str>>();
+        let happiness = match words[2] {
+            "gain" => words[3].parse::<i32>().expect("Should be number"),
+            "lose" => -words[3].parse::<i32>().expect("Should be number"),
+            _ => panic!("Should not happen"),
+        };
+        let person = words[0].to_string();
+        let mut next_to = words[10].to_string();
+        next_to.pop();
+        if !people.contains(&person) {
+            people.push(person.clone());
+        }
+        happiness_table.insert((person, next_to), happiness);
+    });
+
+    for person in &people {
+        happiness_table.insert(("Fabian".to_string(), person.to_owned()), 0);
+        happiness_table.insert((person.to_owned(), "Fabian".to_string()), 0);
+    }
+
+    people.push("Fabian".to_string());
+
+    let num_people = people.len();
+
+    let possible_permutations = factorial(num_people);
+
+    let mut highest_happiness = 0;
+    for idx in 1..possible_permutations {
+        let mut happiness = 0;
+        let permutation = permutation(people.clone(), idx).unwrap();
+
+        for (pos, person) in permutation.clone().iter().enumerate() {
+            let left_neighbor = {
+                if pos == 0 {
+                    permutation[num_people - 1].clone()
+                } else {
+                    permutation[pos - 1].clone()
+                }
+            };
+            let right_neighbor = {
+                if pos == num_people - 1 {
+                    permutation[0].clone()
+                } else {
+                    permutation[pos + 1].clone()
+                }
+            };
+
+            let left_happiness = happiness_table
+                .get(&(person.to_owned(), left_neighbor))
+                .unwrap();
+            let right_happiness = happiness_table
+                .get(&(person.to_owned(), right_neighbor))
+                .unwrap();
+            happiness += left_happiness + right_happiness;
+        }
+
+        if happiness > highest_happiness {
+            highest_happiness = happiness;
+        }
+    }
+
+    highest_happiness
+}
+
+#[cfg(test)]
+mod tests_13 {
+    use super::*;
+
+    const INPUT: &str = "Alice would gain 54 happiness units by sitting next to Bob.
+Alice would lose 79 happiness units by sitting next to Carol.
+Alice would lose 2 happiness units by sitting next to David.
+Bob would gain 83 happiness units by sitting next to Alice.
+Bob would lose 7 happiness units by sitting next to Carol.
+Bob would lose 63 happiness units by sitting next to David.
+Carol would lose 62 happiness units by sitting next to Alice.
+Carol would gain 60 happiness units by sitting next to Bob.
+Carol would gain 55 happiness units by sitting next to David.
+David would gain 46 happiness units by sitting next to Alice.
+David would lose 7 happiness units by sitting next to Bob.
+David would gain 41 happiness units by sitting next to Carol.";
+
+    #[test]
+    fn it_works() {
+        let result = process_part1(INPUT);
+        assert_eq!(result, 330);
+    }
+}

y2015/src/days/mod.rs

@@ -2,6 +2,7 @@ pub mod d1;
 pub mod d10;
 pub mod d11;
 pub mod d12;
+pub mod d13;
 pub mod d2;
 pub mod d3;
 pub mod d4;