day16

src/day10.rs

@@ -28,7 +28,10 @@ fn part2(input: &Vec<u32>) -> i64 {
     let mut ans = HashMap::new();
     ans.insert(0, 1);
     for adapter in input.iter().cloned().map(|x| x as i32) {
-        let to_insert = ans.get(&(adapter as i32 - 1)).unwrap_or(&0) + ans.get(&(adapter as i32 - 2)).unwrap_or(&0) + ans.get(&(adapter as i32 - 3)).unwrap_or(&0);
+        let to_insert = ans.get(&(adapter as i32 - 1)).unwrap_or(&0)
+            + ans.get(&(adapter as i32 - 2)).unwrap_or(&0)
+            + ans.get(&(adapter as i32 - 3)).unwrap_or(&0);
+
         ans.insert(adapter, to_insert.clone());
     }
 

src/day12.rs

@@ -0,0 +1,137 @@
+use aoc_runner_derive::{aoc, aoc_generator};
+
+use Instruction::*;
+use itertools::Itertools;
+
+#[derive(Debug)]
+enum Instruction {
+    MoveNorth(i32),
+    MoveSouth(i32),
+    MoveEast(i32),
+    MoveWest(i32),
+    TurnLeft(i32),
+    TurnRight(i32),
+    MoveForward(i32)
+}
+
+impl From<(char, i32)> for Instruction {
+    fn from(value: (char, i32)) -> Self {
+        match value {
+            (i, v) if i == 'N' => MoveNorth(v),
+            (i, v) if i == 'S' => MoveSouth(v),
+            (i, v) if i == 'E' => MoveEast(v),
+            (i, v) if i == 'W' => MoveWest(v),
+            (i, v) if i == 'L' => TurnLeft(v),
+            (i, v) if i == 'R' => TurnRight(v),
+            (i, v) if i == 'F' => MoveForward(v),
+            _ => unreachable!()
+        }
+    }
+}
+
+#[aoc_generator(day12)]
+fn parse(input: &str) -> Vec<Instruction> {
+    input
+    .lines()
+    .map(|line| {
+        (line.chars().next().unwrap(), line[1..].parse::<i32>().unwrap()).into()
+    })
+    .collect_vec()
+}
+
+const DIR_POS_MODIFIER: [(i32, i32); 4] = [(1, 0), (0, -1), (-1, 0), (0, 1)];
+
+#[aoc(day12, part1)]
+fn part1(input: &Vec<Instruction>) -> i32 {
+    let mut x = 0;
+    let mut y = 0;
+    let mut direction = 0; // 0 is east, thus 90 is south, 180 is west, and 270 is north
+
+    for instr in input {
+        match instr {
+            MoveNorth(val) => y += val,
+            MoveSouth(val) => y -= val,
+            MoveEast(val) => x += val,
+            MoveWest(val) => x -= val,
+            TurnLeft(val) => {
+                direction -= val;
+                if direction < 0 {
+                    direction += 360;
+                }
+            },
+            TurnRight(val) => {
+                direction += val;
+                if direction >= 360 {
+                    direction -= 360
+                }
+            },
+            MoveForward(val) => {
+                let (xmod, ymod) = DIR_POS_MODIFIER[(direction / 90) as usize];
+                x += xmod * val;
+                y += ymod * val;
+            },
+        }
+    }
+
+    x.abs() + y.abs()
+}
+
+#[aoc(day12, part2)]
+fn part2(input: &Vec<Instruction>) -> i32 {
+    let mut way_x = 10;
+    let mut way_y = 1;
+
+    let mut ship_x: i32 = 0;
+    let mut ship_y: i32 = 0;
+
+    for instr in input {
+        match instr {
+            MoveNorth(val) => way_y += val,
+            MoveSouth(val) => way_y -= val,
+            MoveEast(val) => way_x += val,
+            MoveWest(val) => way_x -= val,
+            TurnLeft(val) => {
+                for _ in 0..(val / 90) {
+                    let tmp = way_y;
+                    way_y = way_x;
+                    way_x = -tmp;
+                }
+            },
+            TurnRight(val) => {
+                for _ in 0..(val / 90) {
+                    let tmp = way_y;
+                    way_y = -way_x;
+                    way_x = tmp;
+                }
+            },
+            MoveForward(val) => {
+                ship_x += way_x * val;
+                ship_y += way_y * val;
+            },
+        }
+    }
+
+    ship_x.abs() + ship_y.abs()
+}
+
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+const EX: &str = r"F10
+N3
+F7
+R90
+F11";
+
+    #[test]
+    fn part1_example() {
+        assert_eq!(part1(&parse(EX)), 25);
+    }
+
+    #[test]
+    fn part2_example() {
+        assert_eq!(part2(&parse(EX)), 286);
+    }
+}

src/day13.rs

@@ -0,0 +1,76 @@
+use aoc_runner_derive::{aoc, aoc_generator};
+use itertools::Itertools;
+#[aoc_generator(day13, part1)]
+fn parse(input: &str) -> (i32, Vec<i32>) {
+    let (start, buses) = input
+        .lines()
+        .collect_tuple()
+        .unwrap();
+
+    let buses = buses
+        .split(',')
+        .filter_map(|num| num.parse::<i32>().ok())
+        .collect_vec();
+
+    (start.parse::<i32>().unwrap(), buses)
+}
+
+#[aoc(day13, part1)]
+fn part1((start, buses): &(i32, Vec<i32>)) -> i32 {
+    let mut cur = 0;
+    loop {
+        if let Some(bus) = buses.iter().find(|x| (cur + start) % *x == 0) {
+            return bus * cur;
+        }
+        cur += 1;
+    }
+}
+
+#[aoc_generator(day13, part2)]
+fn parse2(input: &str) -> Vec<Option<i64>> {
+    let buses = input
+        .lines().skip(1).next().unwrap();
+
+    let buses = buses
+        .split(',')
+        .map(|num| num.parse::<i64>().ok())
+        .collect_vec();
+
+    buses
+}
+
+#[aoc(day13, part2)]
+fn part2(input: &Vec<Option<i64>>) -> i64 {
+    let mut min_value = 0;
+    let mut running_product = 1;
+
+    for (index, bus) in input.iter().enumerate() {
+        if let Some(bus) = bus {
+            while (min_value + index as i64) % bus != 0 {
+                min_value += running_product;
+            }
+            running_product *= bus;
+        }
+    }
+
+    min_value
+}
+
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+const EX: &str = r"939
+7,13,x,x,59,x,31,19";
+
+    #[test]
+    fn part1_example() {
+        assert_eq!(part1(&parse(EX)), 295);
+    }
+
+    #[test]
+    fn part2_example() {
+        assert_eq!(part2(&parse2(EX)), 1068781);
+    }
+}

src/day14.rs

@@ -0,0 +1,149 @@
+use std::{collections::HashMap, iter::zip};
+
+use aoc_runner_derive::{aoc, aoc_generator};
+use itertools::{Itertools, iproduct};
+
+#[derive(Debug)]
+enum ProgramStep {
+    Mask(String),
+    Mem(u64, u64)
+}
+
+impl From<&str> for ProgramStep {
+    fn from(value: &str) -> Self {
+        let (name, value) = value.split(" = ").collect_tuple().unwrap();
+
+        return match name {
+            "mask" => Self::Mask(value.to_string()),
+            name if name.starts_with("mem") => {
+                Self::Mem(name[4..name.len() - 1].parse::<u64>().unwrap(), value.parse::<u64>().unwrap())
+            }
+            _ => unreachable!()
+        };
+    }
+}
+
+#[aoc_generator(day14)]
+fn parse(input: &str) -> Vec<ProgramStep> {
+    input.lines().map(ProgramStep::from).collect_vec()
+}
+
+fn apply_mask(mask: &str, val: u64) -> u64 {
+    let mut val = val;
+    for (i, char) in mask.chars().enumerate() {
+        match char {
+            'X' => continue,
+            '1' => val = val | (2_u64.pow((36 - i - 1).try_into().unwrap())),
+            '0' => val = val & !(2_u64.pow((36 - i - 1).try_into().unwrap())),
+            _ => unreachable!()
+        };
+    }
+
+    val
+}
+
+#[aoc(day14, part1)]
+fn part1(program: &Vec<ProgramStep>) -> u64 {
+    let mut mem: HashMap<u64, u64> = HashMap::new();
+    let mut mask = "";
+
+    for step in program {
+        match step {
+            ProgramStep::Mask(val) => mask = val,
+            ProgramStep::Mem(addr, val) => {
+                let val = apply_mask(mask, *val);
+                mem.insert(*addr, val);
+            },
+        }
+    }
+    mem.values().sum()
+}
+
+fn permute_masks(mask: &str) -> Vec<String> {
+    let mut masks: Vec<String> = vec![];
+    let bits = mask.chars().enumerate().filter(|(_, v)| *v == 'X').map(|(i, _)| i).collect_vec();
+    let perms = kproduct("21".to_string(), bits.len() as u32);
+
+    let mut new_mask = mask.to_string();
+    for perm in perms {
+        let bit_vals = zip(bits.clone(), perm.chars()).collect::<HashMap<usize, char>>();
+        for (k, val) in bit_vals {
+            new_mask = new_mask[0..k].to_string() + &val.to_string() + &new_mask[k+1..];
+        }
+        masks.push(new_mask.clone());
+    }
+    masks
+}
+
+fn kproduct(seq: String, k: u32) -> Vec<String> {
+    match k {
+        0 => vec![],
+        1 => seq.chars().map(|c| c.to_string()).collect(),
+        2 => iproduct!(seq.chars(), seq.chars()).map(|(a, b)| format!("{}{}", a, b)).collect(),
+        _ => iproduct!(kproduct(seq.clone(), k - 1), seq.chars()).map(|(a, b)| format!("{}{}", a, b)).collect(),
+    }
+}
+
+fn get_addrs(addr: u64, mask: &str) -> Vec<u64> {
+    let mut addrs = vec![];
+    let masks = permute_masks(mask);
+    for mask in masks {
+        let mut addr = addr;
+        for (i, char) in mask.chars().enumerate() {
+            match char {
+                '1' => addr = addr | (2_u64.pow((36 - i - 1).try_into().unwrap())),
+                '2' => addr = addr & !(2_u64.pow((36 - i - 1).try_into().unwrap())),
+                '0' => continue,
+                _ => unreachable!()
+            }
+        }
+        addrs.push(addr)
+    }
+    addrs
+}
+
+#[aoc(day14, part2)]
+fn part2(program: &Vec<ProgramStep>) -> u64 {
+    let mut mem: HashMap<u64, u64> = HashMap::new();
+    let mut mask = "";
+
+    for step in program {
+        match step {
+            ProgramStep::Mask(val) => mask = val,
+            ProgramStep::Mem(addr, val) => {
+                let addrs = get_addrs(*addr, mask);
+                for addr in addrs {
+                    mem.insert(addr, *val);
+                }
+            },
+        }
+    }
+
+    mem.values().sum()
+}
+
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+const EX: &str = r"mask = XXXXXXXXXXXXXXXXXXXXXXXXXXXXX1XXXX0X
+mem[8] = 11
+mem[7] = 101
+mem[8] = 0";
+
+    #[test]
+    fn part1_example() {
+        assert_eq!(part1(&parse(EX)), 165);
+    }
+
+const EX_2: &str = r"mask = 000000000000000000000000000000X1001X
+mem[42] = 100
+mask = 00000000000000000000000000000000X0XX
+mem[26] = 1";
+
+    #[test]
+    fn part2_example() {
+        assert_eq!(part2(&parse(EX_2)), 208);
+    }
+}

src/day15.rs

@@ -0,0 +1,60 @@
+use std::collections::HashMap;
+
+use aoc_runner_derive::{aoc, aoc_generator};
+use itertools::Itertools;
+
+
+#[aoc_generator(day15)]
+fn parse(input: &str) -> Vec<u64> {
+    input.split(',').map(str::parse::<u64>).map(Result::unwrap).collect_vec()
+}
+
+#[aoc(day15, part1)]
+fn part1(input: &Vec<u64>) -> u64 {
+    let mut list = input.iter().take(input.len() - 1).cloned().enumerate().map(|(i,v)| (v,i)).collect::<HashMap<_, _>>();
+    let mut cur = *input.last().unwrap();
+
+    for turn in input.len() - 1..2020 - 1 {
+        let mut next = 0;
+        if let Some(last_turn) = list.get_mut(&cur) {
+            next = (turn - *last_turn) as u64;
+        }
+        list.insert(cur, turn);
+        cur = next;
+    }
+    cur
+}
+
+#[aoc(day15, part2)]
+fn part2(input: &Vec<u64>) -> u64 {
+    let mut list = input.iter().take(input.len() - 1).cloned().enumerate().map(|(i,v)| (v,i)).collect::<HashMap<_, _>>();
+    let mut cur = *input.last().unwrap();
+
+    for turn in input.len() - 1..30000000 - 1 {
+        let mut next = 0;
+        if let Some(last_turn) = list.get_mut(&cur) {
+            next = (turn - *last_turn) as u64;
+        }
+        list.insert(cur, turn);
+        cur = next;
+    }
+    cur
+}
+
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const EX: &str = r"0,3,6";
+
+    #[test]
+    fn part1_example() {
+        assert_eq!(part1(&parse(EX)), 436);
+    }
+
+    #[test]
+    fn part2_example() {
+        assert_eq!(part2(&parse(EX)), 175594);
+    }
+}

src/day16.rs

@@ -0,0 +1,145 @@
+use std::{ops::RangeInclusive, collections::HashSet};
+
+use aoc_runner_derive::{aoc, aoc_generator};
+use itertools::Itertools;
+use regex::Regex;
+
+lazy_static!(
+    static ref RULE_RE: Regex = Regex::new(r"(.*): (\d+)-(\d+) or (\d+)-(\d+)").unwrap();
+);
+
+#[aoc_generator(day16)]
+fn parse(input: &str) -> (Vec<(String, RangeInclusive<usize>, RangeInclusive<usize>)>, Vec<usize>, Vec<Vec<usize>>) {
+    let (rules, my_ticket, tickets) = input
+    .split("\n\n")
+    .collect_tuple()
+    .unwrap();
+
+    let rules = RULE_RE
+    .captures_iter(rules)
+    .filter_map(|captures| {
+        Some((
+            captures.get(1)?.as_str().to_string(),
+            captures.get(2)?.as_str().parse::<usize>().ok()?..=captures.get(3)?.as_str().parse::<usize>().ok()?,
+            captures.get(4)?.as_str().parse::<usize>().ok()?..=captures.get(5)?.as_str().parse::<usize>().ok()?,
+        ))
+    }).collect_vec();
+
+    let my_ticket = my_ticket
+    .lines()
+    .last()
+    .unwrap()
+    .split(',')
+    .filter_map(|num| num.parse::<usize>().ok())
+    .collect_vec();
+
+    let tickets = tickets
+    .lines()
+    .skip(1)
+    .map(|line| {
+        line
+        .split(',')
+        .filter_map(|num| num.parse::<usize>().ok())
+        .collect_vec()
+    }).collect_vec();
+
+    (rules, my_ticket, tickets)
+}
+
+#[aoc(day16, part1)]
+fn part1((rules, _, tickets): &(Vec<(String, RangeInclusive<usize>, RangeInclusive<usize>)>, Vec<usize>, Vec<Vec<usize>>)) -> usize {
+    let mut invalid = 0;
+    for ticket in tickets {
+        for item in ticket {
+            if !rules.iter().any(|rule| {
+                rule.1.contains(item) || rule.2.contains(item)
+            }) {
+                invalid += item;
+            }
+        }
+    }
+
+    invalid
+}
+
+#[aoc(day16, part2)]
+fn part2((rules, my_ticket, tickets): &(Vec<(String, RangeInclusive<usize>, RangeInclusive<usize>)>, Vec<usize>, Vec<Vec<usize>>)) -> usize {
+    let mut tickets = tickets.clone();
+    let mut rem = 0;
+    for (i, ticket) in tickets.clone().iter().enumerate() {
+        for item in ticket {
+            if !rules.iter().any(|rule| {
+                rule.1.contains(item) || rule.2.contains(item)
+            }) {
+                tickets.remove(i - rem);
+                rem += 1;
+            }
+        }
+    }
+
+    let mut possible_rules = get_possible_rules(&tickets, rules);
+    let mut assigned_rules = [0; 20];
+    while let Some(i) = possible_rules.iter().position(|s| s.len() == 1) {
+        let v = *possible_rules[i].iter().next().unwrap();
+        assigned_rules[i] = v;
+        for s in &mut possible_rules { s.remove(&v); }
+    }
+    assigned_rules.iter()
+        .enumerate()
+        .filter(|(_,&rule)| rule < 6)
+        .map(|(i,_)| my_ticket[i])
+        .product()
+}
+
+fn get_possible_rules(tickets: &Vec<Vec<usize>>, rules: &Vec<(String, RangeInclusive<usize>, RangeInclusive<usize>)>) -> Vec<HashSet<usize>> {
+    (0..20).map(|i|
+        (0..20).filter(|&j|
+            tickets.iter().all(|t| fits_rule(&rules[j], t[i]))
+        ).collect()
+    ).collect()
+}
+
+fn fits_rule((_, r1,r2): &(String, RangeInclusive<usize>, RangeInclusive<usize>), v: usize) -> bool {
+    r1.contains(&v) || r2.contains(&v)
+}
+
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+const EX: &str = r"class: 1-3 or 5-7
+row: 6-11 or 33-44
+seat: 13-40 or 45-50
+
+your ticket:
+7,1,14
+
+nearby tickets:
+7,3,47
+40,4,50
+55,2,20
+38,6,12";
+
+    #[test]
+    fn part1_example() {
+        assert_eq!(part1(&parse(EX)), 71);
+    }
+
+const EX2: &str = r"class: 0-1 or 4-19
+row: 0-5 or 8-19
+seat: 0-13 or 16-19
+
+your ticket:
+11,12,13
+
+nearby tickets:
+3,9,18
+15,1,5
+5,14,9";
+
+    #[test]
+    fn part2_example() {
+        assert_eq!(part2(&parse(EX2)), 1716);
+    }
+}

src/day9.rs

@@ -1,7 +1,7 @@
 use aoc_runner_derive::{aoc, aoc_generator};
 use itertools::Itertools;
 
-const PREAMBLE_LEN: usize = 25;
+const PREAMBLE_LEN: usize = 5;
 
 #[aoc_generator(day9)]
 fn parse(input: &str) -> Vec<u64> {

src/lib.rs

@@ -1,3 +1,8 @@
+mod day16;
+mod day15;
+mod day14;
+mod day13;
+mod day12;
 mod day10;
 mod day9;
 mod day8;