diff --git a/rust/src/day01.rs b/rust/src/day01.rs
new file mode 100644
index 0000000..bd35b81
--- /dev/null
+++ b/rust/src/day01.rs
@@ -0,0 +1,33 @@
+use std::{collections::HashMap, time::Duration, time::Instant};
+
+pub fn run(print: bool) -> Duration {
+    let file_string = std::fs::read_to_string("inputs/day01").unwrap();
+    let instant = Instant::now();
+
+    let entries: Vec<usize> = file_string.lines().flat_map(|line| line.parse()).collect();
+    let mut sums = HashMap::new();
+
+    let mut part1 = None;
+    for i in &entries {
+        for j in &entries {
+            if i + j < 2020 {
+                sums.insert(i + j, i * j);
+            } else if i + j == 2020 {
+                part1 = Some(i * j);
+            }
+        }
+    }
+    let part1 = part1.unwrap();
+
+    let part2 = entries
+        .iter()
+        .find_map(|i| sums.get(&(2020 - i)).map(|mul| i * mul))
+        .unwrap();
+
+    let elapsed = instant.elapsed();
+    if print {
+        dbg!(elapsed, part1, part2);
+    }
+
+    elapsed
+}
diff --git a/rust/src/day02.rs b/rust/src/day02.rs
new file mode 100644
index 0000000..4f3ca55
--- /dev/null
+++ b/rust/src/day02.rs
@@ -0,0 +1,47 @@
+use std::time::{Duration, Instant};
+
+pub fn run(print: bool) -> Duration {
+    let file_string = std::fs::read_to_string("inputs/day02").unwrap();
+    let instant = Instant::now();
+
+    let rules: Vec<(usize, usize, char, &str)> = file_string
+        .lines()
+        .flat_map(|rule| {
+            let mut splitc = rule.splitn(2, ' ');
+            let mut split_range = splitc.next()?.split('-');
+
+            let min: usize = split_range.next()?.parse().ok()?;
+            let max: usize = split_range.next()?.parse().ok()?;
+
+            let rest = splitc.next()?;
+            let c = rest.chars().next()?;
+            let pw = &rest[3..];
+
+            Some((min, max, c, pw))
+        })
+        .collect();
+
+    let part1 = rules
+        .iter()
+        .filter(|(min, max, c, pw)| {
+            let c = &pw.chars().filter(|n| n == c).count();
+            min <= c && c <= max
+        })
+        .count();
+
+    let part2 = rules
+        .iter()
+        .filter(|(min, max, c, pw)| {
+            let mut chars = pw.chars();
+            let a = chars.nth(min - 1) == Some(*c);
+            let b = chars.nth(max - min - 1) == Some(*c);
+            a ^ b
+        })
+        .count();
+
+    let elapsed = instant.elapsed();
+    if print {
+        dbg!(elapsed, part1, part2);
+    }
+    elapsed
+}
diff --git a/rust/src/day03.rs b/rust/src/day03.rs
new file mode 100644
index 0000000..bd06199
--- /dev/null
+++ b/rust/src/day03.rs
@@ -0,0 +1,42 @@
+use std::time::{Duration, Instant};
+
+fn count(rows: &[Vec<char>], dx: usize, dy: usize) -> usize {
+    let mut x = 0;
+    let mut trees = 0;
+    for y in (0..rows.len()).step_by(dy) {
+        let row = &rows[y];
+
+        if row[x] == '#' {
+            trees += 1;
+        }
+
+        x = (x + dx) % row.len();
+    }
+    trees
+}
+
+pub fn run(print: bool) -> Duration {
+    let file_string = std::fs::read_to_string("inputs/day3").unwrap();
+
+    let instant = Instant::now();
+
+    let rows: Vec<Vec<char>> = file_string
+        .lines()
+        .map(|line| line.chars().collect())
+        .collect();
+
+    let part1 = count(&rows, 3, 1);
+
+    let part2 = part1
+        * [(1, 1), (5, 1), (7, 1), (1, 2)]
+            .iter()
+            .map(|(dx, dy)| count(&rows, *dx, *dy))
+            .fold(1, |acc, element| acc * element);
+
+    let elapsed = instant.elapsed();
+    if print {
+        dbg!(elapsed, part1, part2);
+    }
+
+    elapsed
+}
diff --git a/rust/src/day04.rs b/rust/src/day04.rs
new file mode 100644
index 0000000..fc24f88
--- /dev/null
+++ b/rust/src/day04.rs
@@ -0,0 +1,75 @@
+use std::time::{Duration, Instant};
+
+fn between(field: &str, lower: i32, higher: i32) -> bool {
+    let n: i32 = field.parse().unwrap();
+    n >= lower && n <= higher
+}
+
+pub fn run(print: bool) -> Duration {
+    let input = std::fs::read_to_string("inputs/day04").unwrap();
+
+    let now = Instant::now();
+
+    let passports: Vec<_> = input
+        .split("\n\n")
+        .map(|p| p.replace('\n', " ").trim().to_string())
+        .collect();
+
+    let valid_passports = passports.iter().filter(|p| {
+        p.contains("byr")
+            && p.contains("iyr")
+            && p.contains("eyr")
+            && p.contains("hgt")
+            && p.contains("hcl")
+            && p.contains("ecl")
+            && p.contains("pid")
+    });
+
+    let mut part1 = 0;
+
+    let part2 = valid_passports
+        .filter(|p| {
+            part1 += 1;
+
+            let mut valid = true;
+            for field in p.split(' ') {
+                let mut parts = field.split(':');
+                let label = parts.next().unwrap();
+                let value = parts.next().unwrap();
+
+                valid = valid
+                    && match label {
+                        "byr" => between(value, 1920, 2002),
+                        "iyr" => between(value, 2010, 2020),
+                        "eyr" => between(value, 2020, 2030),
+                        "hgt" => {
+                            let height = &value[..value.len() - 2];
+                            (value.ends_with("in") && between(height, 59, 76))
+                                || (value.ends_with("cm") && between(height, 150, 193))
+                        }
+                        "hcl" => value.starts_with("#"),
+                        "ecl" => {
+                            value == "amb"
+                                || value == "blu"
+                                || value == "brn"
+                                || value == "gry"
+                                || value == "grn"
+                                || value == "hzl"
+                                || value == "oth"
+                        }
+                        "pid" => value.len() == 9,
+                        "cid" => true,
+                        _ => false,
+                    }
+            }
+            valid
+        })
+        .count();
+
+    let elapsed = now.elapsed();
+    if print {
+        dbg!(elapsed, part1, part2);
+    }
+
+    elapsed
+}
diff --git a/rust/src/day05.rs b/rust/src/day05.rs
new file mode 100644
index 0000000..66dc7e2
--- /dev/null
+++ b/rust/src/day05.rs
@@ -0,0 +1,51 @@
+use std::time::{Duration, Instant};
+
+pub fn run(print: bool) -> Duration {
+    let input = std::fs::read_to_string("inputs/day05").unwrap();
+    let instant = Instant::now();
+
+    let passes: Vec<_> = input.lines().collect();
+    let mut ids: Vec<_> = passes
+        .iter()
+        .map(|pass| {
+            let mut row_min = 0;
+            let mut row_max = 128;
+            let mut column_min = 0;
+            let mut column_max = 8;
+
+            for c in pass.chars() {
+                match c {
+                    'F' => row_max = (row_min + row_max) / 2,
+                    'B' => row_min = (row_min + row_max) / 2,
+                    'L' => column_max = (column_min + column_max) / 2,
+                    'R' => column_min = (column_min + column_max) / 2,
+                    _ => (),
+                };
+            }
+
+            row_min * 8 + column_min
+        })
+        .collect();
+
+    ids.sort();
+
+    let part1 = ids.iter().max().unwrap();
+
+    let part2 = ids
+        .windows(2)
+        .find_map(|window| {
+            if window[0] + 2 == window[1] {
+                Some(window[0] + 1)
+            } else {
+                None
+            }
+        })
+        .unwrap();
+
+    let elapsed = instant.elapsed();
+    if print {
+        dbg!(elapsed, part1, part2);
+    }
+
+    elapsed
+}
diff --git a/rust/src/day08.rs b/rust/src/day08.rs
new file mode 100644
index 0000000..0cf4aa5
--- /dev/null
+++ b/rust/src/day08.rs
@@ -0,0 +1,95 @@
+use std::{
+    collections::HashSet,
+    time::{Duration, Instant},
+};
+
+#[derive(Debug, Copy, Clone)]
+enum Instruction {
+    Acc(i32),
+    Jmp(i32),
+    Nop,
+}
+
+fn part1(instructions: &[Instruction]) -> (i32, Vec<i32>) {
+    let mut accumulator = 0;
+    let mut pc = 0;
+    let mut pc_history = HashSet::new();
+    let mut jumps = Vec::new();
+
+    loop {
+        match instructions[pc as usize] {
+            Instruction::Acc(i) => accumulator += i,
+            Instruction::Jmp(i) => {
+                let target = pc + i - 1;
+                if !pc_history.insert(target) {
+                    break (accumulator, jumps);
+                }
+
+                jumps.push(pc);
+                pc += i - 1
+            }
+            Instruction::Nop => (),
+        };
+
+        pc += 1;
+    }
+}
+
+fn part2(instructions: &[Instruction], skip: i32) -> Option<i32> {
+    let mut accumulator = 0;
+    let mut pc = 0;
+    let mut pc_history = HashSet::new();
+
+    loop {
+        if pc != skip {
+            match instructions.get(pc as usize) {
+                Some(Instruction::Acc(i)) => accumulator += i,
+                Some(Instruction::Jmp(i)) => {
+                    let target = pc + i;
+                    if !pc_history.insert(target) {
+                        break None;
+                    }
+
+                    pc = target - 1;
+                }
+                Some(Instruction::Nop) => (),
+                None => break Some(accumulator),
+            };
+        }
+
+        pc += 1;
+    }
+}
+
+pub fn run(print: bool) -> Duration {
+    let input = std::fs::read_to_string("inputs/day08").unwrap();
+    let instant = Instant::now();
+
+    let instructions: Vec<_> = input
+        .lines()
+        .map(|line| {
+            let operation = &line[0..3];
+            let value: i32 = line[4..].parse().unwrap();
+            match operation {
+                "acc" => Instruction::Acc(value),
+                "jmp" => Instruction::Jmp(value),
+                "nop" => Instruction::Nop,
+                _ => unreachable!(operation),
+            }
+        })
+        .collect();
+
+    let (part1, jumps) = part1(&instructions);
+
+    let part2 = jumps
+        .iter()
+        .rev()
+        .find_map(|skip_pc| part2(&instructions, *skip_pc))
+        .unwrap();
+
+    let elapsed = instant.elapsed();
+    if print {
+        dbg!(elapsed, part1, part2);
+    }
+    elapsed
+}
diff --git a/rust/src/day09.rs b/rust/src/day09.rs
new file mode 100644
index 0000000..0cf1a60
--- /dev/null
+++ b/rust/src/day09.rs
@@ -0,0 +1,58 @@
+use std::time::{Duration, Instant};
+
+fn part1(numbers: &[usize]) -> usize {
+    'outer: for i in COUNT..numbers.len() {
+        for x in i - COUNT..i {
+            if numbers[x] > numbers[i] {
+                continue;
+            }
+
+            for y in x + 1..i {
+                if numbers[x] + numbers[y] == numbers[i] {
+                    continue 'outer;
+                }
+            }
+        }
+
+        return numbers[i];
+    }
+
+    panic!();
+}
+
+fn part2(numbers: &[usize], part1: usize) -> usize {
+    let mut lower = 0;
+    let mut upper = 0;
+    let mut sum = 0;
+
+    while sum != part1 {
+        while sum < part1 {
+            sum += numbers[upper];
+            upper += 1;
+        }
+
+        while sum > part1 {
+            sum -= numbers[lower];
+            lower += 1;
+        }
+    }
+
+    let slice = &numbers[lower..upper];
+    slice.iter().min().unwrap() + slice.iter().max().unwrap()
+}
+
+const COUNT: usize = 25;
+pub fn run(print: bool) -> Duration {
+    let input = std::fs::read_to_string("../inputs/09").unwrap();
+    let instant = Instant::now();
+
+    let numbers: Vec<usize> = input.split('\n').flat_map(str::parse).collect();
+    let part1 = part1(&numbers);
+    let part2 = part2(&numbers, part1);
+
+    if print {
+        dbg!(part1, part2);
+    }
+
+    instant.elapsed()
+}
diff --git a/rust/src/day15.rs b/rust/src/day15.rs
new file mode 100644
index 0000000..e8e307c
--- /dev/null
+++ b/rust/src/day15.rs
@@ -0,0 +1,37 @@
+use std::time::{Duration, Instant};
+
+const END: usize = 30_000_000;
+pub fn run(print: bool) -> Duration {
+    let input: Vec<usize> = "0,1,5,10,3,12,19"
+        .split(",")
+        .map(|i| i.parse().unwrap())
+        .collect();
+    let instant = Instant::now();
+
+    let mut history = vec![0; END];
+    let mut last = input[0];
+    for turn in 0..input.len() {
+        history[last] = turn;
+        last = input[turn];
+    }
+
+    for turn in input.len()..2020 {
+        let stored = history[last];
+        history[last] = turn;
+        last = if stored == 0 { 0 } else { turn - stored };
+    }
+    if print {
+        println!("Part 1: {}", last);
+    }
+
+    for turn in 2020..END {
+        let stored = history[last];
+        history[last] = turn;
+        last = if stored == 0 { 0 } else { turn - stored };
+    }
+    if print {
+        println!("Part 2: {}", last);
+    }
+
+    instant.elapsed()
+}
diff --git a/rust/src/day16.rs b/rust/src/day16.rs
new file mode 100644
index 0000000..76fc4f2
--- /dev/null
+++ b/rust/src/day16.rs
@@ -0,0 +1,148 @@
+use std::fmt;
+use std::time::{Duration, Instant};
+
+type Ticket = Vec<usize>;
+
+#[derive(PartialEq, Eq, Hash)]
+struct Range {
+    from: usize,
+    to: usize,
+}
+
+impl fmt::Debug for Range {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.write_fmt(format_args!("{} - {}", self.from, self.to))
+    }
+}
+impl Range {
+    fn from(s: &str) -> Self {
+        let mut range = s.split("-");
+        Self {
+            from: range.next().unwrap().parse().unwrap(),
+            to: range.next().unwrap().parse().unwrap(),
+        }
+    }
+
+    fn contains(&self, i: usize) -> bool {
+        i >= self.from && i <= self.to
+    }
+}
+
+#[derive(Debug, PartialEq, Eq, Hash)]
+struct Rule {
+    name: String,
+    ranges: (Range, Range),
+}
+
+impl Rule {
+    fn validate(&self, i: usize) -> bool {
+        let (a, b) = &self.ranges;
+        a.contains(i) || b.contains(i)
+    }
+}
+
+pub fn run(print: bool) -> Duration {
+    let input = std::fs::read_to_string("../inputs/16").unwrap();
+    let instant = Instant::now();
+
+    let mut lines = input.lines();
+    let mut rules = Vec::new();
+    while let Some(line) = lines.next() {
+        let mut colon_split = line.split(": ");
+        let name = colon_split.next().unwrap().to_string();
+        if name.is_empty() {
+            break;
+        }
+
+        let mut ranges = colon_split.next().unwrap().split(" or ");
+
+        rules.push(Rule {
+            name,
+            ranges: (
+                Range::from(ranges.next().unwrap()),
+                Range::from(ranges.next().unwrap()),
+            ),
+        });
+    }
+
+    lines.next(); // "your ticket:"
+
+    let your_ticket: Ticket = lines
+        .next()
+        .unwrap()
+        .split(",")
+        .map(|s| s.parse().unwrap())
+        .collect();
+
+    lines.next(); // ""
+    lines.next(); // "nearby tickets:"
+
+    let mut nearby_tickets: Vec<Ticket> = Vec::new();
+    while let Some(line) = lines.next() {
+        nearby_tickets.push(line.split(",").map(|s| s.parse().unwrap()).collect());
+    }
+
+    let mut part1 = 0;
+    let mut valid_tickets = Vec::new();
+    for ticket in &nearby_tickets {
+        let mut valid = true;
+        for &field in ticket {
+            let rule = rules.iter().find(|rule| rule.validate(field));
+            if rule.is_none() {
+                valid = false;
+                part1 += field;
+            }
+        }
+
+        if valid {
+            valid_tickets.push(ticket);
+        }
+    }
+
+    if print {
+        dbg!(part1);
+    }
+
+    let mut field_possibilities: Vec<_> = (0..your_ticket.len())
+        .map(|_| (0..rules.len()).collect::<Vec<_>>())
+        .collect();
+
+    for ticket in valid_tickets {
+        for (&field, possibilities) in ticket.iter().zip(field_possibilities.iter_mut()) {
+            possibilities
+                .iter()
+                .position(|&rule_i| !rules[rule_i].validate(field))
+                .map(|i| possibilities.remove(i));
+        }
+    }
+
+    let mut part2 = 1;
+    loop {
+        let field_possibility = field_possibilities
+            .iter()
+            .enumerate()
+            .find(|(_, fp)| fp.len() == 1);
+
+        let (i, possibility) = match field_possibility {
+            Some((i, v)) => (i, v[0]),
+            None => break,
+        };
+
+        for fp in field_possibilities.iter_mut() {
+            fp.iter()
+                .position(|&i| i == possibility)
+                .map(|i| fp.remove(i));
+        }
+
+        let rule = &rules[possibility].name;
+        if rule.starts_with("de") {
+            part2 *= your_ticket[i];
+        }
+    }
+
+    if print {
+        dbg!(part2);
+    }
+
+    instant.elapsed()
+}
diff --git a/rust/src/day19.rs b/rust/src/day19.rs
new file mode 100644
index 0000000..d3f1700
--- /dev/null
+++ b/rust/src/day19.rs
@@ -0,0 +1,116 @@
+use std::collections::BTreeMap as HashMap;
+use std::fs::File;
+use std::io::{BufWriter, Write};
+use std::time::{Duration, Instant};
+
+#[derive(Debug)]
+enum Rhs {
+    Terminal(char),
+    Variables(Vec<Vec<usize>>),
+}
+
+type Rules = HashMap<usize, Rhs>;
+
+fn parse(input: &str) -> Option<(Rules, Vec<&str>)> {
+    let mut rules = HashMap::new();
+    let mut messages = Vec::new();
+    let mut parsing_rules = true;
+    for line in input.lines() {
+        let trim = line.trim();
+        if trim.is_empty() {
+            parsing_rules = false;
+            continue;
+        }
+
+        if parsing_rules {
+            let mut split = trim.split(": ");
+            let lhs: usize = split.next()?.parse().ok()?;
+
+            let terms = split.next()?;
+            let rhs = if terms.starts_with('"') {
+                Rhs::Terminal(terms.chars().nth(1)?)
+            } else {
+                Rhs::Variables(
+                    terms
+                        .split(" | ")
+                        .map(|t| t.split(" ").flat_map(str::parse).collect())
+                        .collect(),
+                )
+            };
+
+            rules.insert(lhs, rhs);
+        } else {
+            messages.push(trim);
+        }
+    }
+
+    Some((rules, messages))
+}
+
+fn generate(rules: &Rules, messages: &Vec<&str>, filename: &str) -> std::io::Result<()> {
+    let write_file = File::create(filename)?;
+    let mut w = BufWriter::new(&write_file);
+
+    writeln!(&mut w, "from typing import Tuple")?;
+    writeln!(&mut w)?;
+
+    for (i, rule) in rules.iter() {
+        writeln!(&mut w, "def rule_{}(s):", i)?;
+        writeln!(&mut w, "    if s != '':")?;
+
+        match rule {
+            Rhs::Terminal(terminal) => {
+                writeln!(&mut w, "        if s[0] == '{}':", terminal)?;
+                writeln!(&mut w, "            yield s[1:]")?;
+            }
+
+            Rhs::Variables(variables) => {
+                for term in variables {
+                    for (j, rule) in term.iter().enumerate() {
+                        if j == 0 {
+                            writeln!(&mut w, "        v{} = rule_{}(s)", j, rule)?;
+                        } else {
+                            writeln!(
+                                &mut w,
+                                "        v{} = (out for inp in v{} for out in rule_{}(inp))",
+                                j,
+                                j - 1,
+                                rule,
+                            )?;
+                        }
+                    }
+                    writeln!(&mut w, "        yield from v{}", term.len() - 1)?;
+                    writeln!(&mut w)?;
+                }
+            }
+        }
+
+        writeln!(&mut w)?;
+    }
+    writeln!(&mut w, "def validate(s):")?;
+    writeln!(&mut w, "    return any(x == '' for x in rule_0(s))")?;
+
+    writeln!(&mut w)?;
+    writeln!(&mut w, "if __name__ == '__main__':")?;
+    writeln!(&mut w, "    result = 0")?;
+    for message in messages {
+        writeln!(&mut w, "    result += validate('{}')", message)?;
+    }
+    writeln!(&mut w, "    print('Result:', result)")?;
+
+    Ok(())
+}
+
+pub fn run(_print: bool) -> Duration {
+    let input = std::fs::read_to_string("../inputs/19").unwrap();
+    let instant = Instant::now();
+
+    let (mut rules, messages) = parse(&input).unwrap();
+    generate(&rules, &messages, "/tmp/day19-1.py").unwrap();
+
+    rules.insert(8, Rhs::Variables(vec![vec![42], vec![42, 8]]));
+    rules.insert(11, Rhs::Variables(vec![vec![42, 31], vec![42, 11, 31]]));
+    generate(&rules, &messages, "/tmp/day19-2.py").unwrap();
+
+    instant.elapsed()
+}
diff --git a/rust/src/main.rs b/rust/src/main.rs
index 2d6e978..ab8477e 100644
--- a/rust/src/main.rs
+++ b/rust/src/main.rs
@@ -1,808 +1,27 @@
 use std::time::Duration;
 
-mod day01 {
-    use std::{collections::HashMap, time::Duration, time::Instant};
-
-    pub fn run(print: bool) -> Duration {
-        let file_string = std::fs::read_to_string("inputs/day01").unwrap();
-        let instant = Instant::now();
-
-        let entries: Vec<usize> = file_string.lines().flat_map(|line| line.parse()).collect();
-        let mut sums = HashMap::new();
-
-        let mut part1 = None;
-        for i in &entries {
-            for j in &entries {
-                if i + j < 2020 {
-                    sums.insert(i + j, i * j);
-                } else if i + j == 2020 {
-                    part1 = Some(i * j);
-                }
-            }
-        }
-        let part1 = part1.unwrap();
-
-        let part2 = entries
-            .iter()
-            .find_map(|i| sums.get(&(2020 - i)).map(|mul| i * mul))
-            .unwrap();
-
-        let elapsed = instant.elapsed();
-        if print {
-            dbg!(elapsed, part1, part2);
-        }
-
-        elapsed
-    }
-}
-
-mod day02 {
-    use std::time::{Duration, Instant};
-
-    pub fn run(print: bool) -> Duration {
-        let file_string = std::fs::read_to_string("inputs/day02").unwrap();
-        let instant = Instant::now();
-
-        let rules: Vec<(usize, usize, char, &str)> = file_string
-            .lines()
-            .flat_map(|rule| {
-                let mut splitc = rule.splitn(2, ' ');
-                let mut split_range = splitc.next()?.split('-');
-
-                let min: usize = split_range.next()?.parse().ok()?;
-                let max: usize = split_range.next()?.parse().ok()?;
-
-                let rest = splitc.next()?;
-                let c = rest.chars().next()?;
-                let pw = &rest[3..];
-
-                Some((min, max, c, pw))
-            })
-            .collect();
-
-        let part1 = rules
-            .iter()
-            .filter(|(min, max, c, pw)| {
-                let c = &pw.chars().filter(|n| n == c).count();
-                min <= c && c <= max
-            })
-            .count();
-
-        let part2 = rules
-            .iter()
-            .filter(|(min, max, c, pw)| {
-                let mut chars = pw.chars();
-                let a = chars.nth(min - 1) == Some(*c);
-                let b = chars.nth(max - min - 1) == Some(*c);
-                a ^ b
-            })
-            .count();
-
-        let elapsed = instant.elapsed();
-        if print {
-            dbg!(elapsed, part1, part2);
-        }
-        elapsed
-    }
-}
-
-mod day03 {
-    use std::time::{Duration, Instant};
-
-    fn count(rows: &[Vec<char>], dx: usize, dy: usize) -> usize {
-        let mut x = 0;
-        let mut trees = 0;
-        for y in (0..rows.len()).step_by(dy) {
-            let row = &rows[y];
-
-            if row[x] == '#' {
-                trees += 1;
-            }
-
-            x = (x + dx) % row.len();
-        }
-        trees
-    }
-
-    pub fn run(print: bool) -> Duration {
-        let file_string = std::fs::read_to_string("inputs/day3").unwrap();
-
-        let instant = Instant::now();
-
-        let rows: Vec<Vec<char>> = file_string
-            .lines()
-            .map(|line| line.chars().collect())
-            .collect();
-
-        let part1 = count(&rows, 3, 1);
-
-        let part2 = part1
-            * [(1, 1), (5, 1), (7, 1), (1, 2)]
-                .iter()
-                .map(|(dx, dy)| count(&rows, *dx, *dy))
-                .fold(1, |acc, element| acc * element);
-
-        let elapsed = instant.elapsed();
-        if print {
-            dbg!(elapsed, part1, part2);
-        }
-
-        elapsed
-    }
-}
-
-mod day04 {
-    use std::time::{Duration, Instant};
-
-    fn between(field: &str, lower: i32, higher: i32) -> bool {
-        let n: i32 = field.parse().unwrap();
-        n >= lower && n <= higher
-    }
-
-    pub fn run(print: bool) -> Duration {
-        let input = std::fs::read_to_string("inputs/day04").unwrap();
-
-        let now = Instant::now();
-
-        let passports: Vec<_> = input
-            .split("\n\n")
-            .map(|p| p.replace('\n', " ").trim().to_string())
-            .collect();
-
-        let valid_passports = passports.iter().filter(|p| {
-            p.contains("byr")
-                && p.contains("iyr")
-                && p.contains("eyr")
-                && p.contains("hgt")
-                && p.contains("hcl")
-                && p.contains("ecl")
-                && p.contains("pid")
-        });
-
-        let mut part1 = 0;
-
-        let part2 = valid_passports
-            .filter(|p| {
-                part1 += 1;
-
-                let mut valid = true;
-                for field in p.split(' ') {
-                    let mut parts = field.split(':');
-                    let label = parts.next().unwrap();
-                    let value = parts.next().unwrap();
-
-                    valid = valid
-                        && match label {
-                            "byr" => between(value, 1920, 2002),
-                            "iyr" => between(value, 2010, 2020),
-                            "eyr" => between(value, 2020, 2030),
-                            "hgt" => {
-                                let height = &value[..value.len() - 2];
-                                (value.ends_with("in") && between(height, 59, 76))
-                                    || (value.ends_with("cm") && between(height, 150, 193))
-                            }
-                            "hcl" => value.starts_with("#"),
-                            "ecl" => {
-                                value == "amb"
-                                    || value == "blu"
-                                    || value == "brn"
-                                    || value == "gry"
-                                    || value == "grn"
-                                    || value == "hzl"
-                                    || value == "oth"
-                            }
-                            "pid" => value.len() == 9,
-                            "cid" => true,
-                            _ => false,
-                        }
-                }
-                valid
-            })
-            .count();
-
-        let elapsed = now.elapsed();
-        if print {
-            dbg!(elapsed, part1, part2);
-        }
-
-        elapsed
-    }
-}
-
-mod day05 {
-    use std::time::{Duration, Instant};
-
-    pub fn run(print: bool) -> Duration {
-        let input = std::fs::read_to_string("inputs/day05").unwrap();
-        let instant = Instant::now();
-
-        let passes: Vec<_> = input.lines().collect();
-        let mut ids: Vec<_> = passes
-            .iter()
-            .map(|pass| {
-                let mut row_min = 0;
-                let mut row_max = 128;
-                let mut column_min = 0;
-                let mut column_max = 8;
-
-                for c in pass.chars() {
-                    match c {
-                        'F' => row_max = (row_min + row_max) / 2,
-                        'B' => row_min = (row_min + row_max) / 2,
-                        'L' => column_max = (column_min + column_max) / 2,
-                        'R' => column_min = (column_min + column_max) / 2,
-                        _ => (),
-                    };
-                }
-
-                row_min * 8 + column_min
-            })
-            .collect();
-
-        ids.sort();
-
-        let part1 = ids.iter().max().unwrap();
-
-        let part2 = ids
-            .windows(2)
-            .find_map(|window| {
-                if window[0] + 2 == window[1] {
-                    Some(window[0] + 1)
-                } else {
-                    None
-                }
-            })
-            .unwrap();
-
-        let elapsed = instant.elapsed();
-        if print {
-            dbg!(elapsed, part1, part2);
-        }
-
-        elapsed
-    }
-}
-
-mod day06 {
-    use std::time::Duration;
-
-    pub fn run(_: bool) -> Duration {
-        Duration::new(0, 0)
-    }
-}
-
-mod day07 {
-    use std::time::Duration;
-
-    pub fn run(_: bool) -> Duration {
-        Duration::new(0, 0)
-    }
-}
-
-mod day08 {
-    use std::{
-        collections::HashSet,
-        time::{Duration, Instant},
-    };
-
-    #[derive(Debug, Copy, Clone)]
-    enum Instruction {
-        Acc(i32),
-        Jmp(i32),
-        Nop,
-    }
-
-    fn part1(instructions: &[Instruction]) -> (i32, Vec<i32>) {
-        let mut accumulator = 0;
-        let mut pc = 0;
-        let mut pc_history = HashSet::new();
-        let mut jumps = Vec::new();
-
-        loop {
-            match instructions[pc as usize] {
-                Instruction::Acc(i) => accumulator += i,
-                Instruction::Jmp(i) => {
-                    let target = pc + i - 1;
-                    if !pc_history.insert(target) {
-                        break (accumulator, jumps);
-                    }
-
-                    jumps.push(pc);
-                    pc += i - 1
-                }
-                Instruction::Nop => (),
-            };
-
-            pc += 1;
-        }
-    }
-
-    fn part2(instructions: &[Instruction], skip: i32) -> Option<i32> {
-        let mut accumulator = 0;
-        let mut pc = 0;
-        let mut pc_history = HashSet::new();
-
-        loop {
-            if pc != skip {
-                match instructions.get(pc as usize) {
-                    Some(Instruction::Acc(i)) => accumulator += i,
-                    Some(Instruction::Jmp(i)) => {
-                        let target = pc + i;
-                        if !pc_history.insert(target) {
-                            break None;
-                        }
-
-                        pc = target - 1;
-                    }
-                    Some(Instruction::Nop) => (),
-                    None => break Some(accumulator),
-                };
-            }
-
-            pc += 1;
-        }
-    }
-
-    pub fn run(print: bool) -> Duration {
-        let input = std::fs::read_to_string("inputs/day08").unwrap();
-        let instant = Instant::now();
-
-        let instructions: Vec<_> = input
-            .lines()
-            .map(|line| {
-                let operation = &line[0..3];
-                let value: i32 = line[4..].parse().unwrap();
-                match operation {
-                    "acc" => Instruction::Acc(value),
-                    "jmp" => Instruction::Jmp(value),
-                    "nop" => Instruction::Nop,
-                    _ => unreachable!(operation),
-                }
-            })
-            .collect();
-
-        let (part1, jumps) = part1(&instructions);
-
-        let part2 = jumps
-            .iter()
-            .rev()
-            .find_map(|skip_pc| part2(&instructions, *skip_pc))
-            .unwrap();
-
-        let elapsed = instant.elapsed();
-        if print {
-            dbg!(elapsed, part1, part2);
-        }
-        elapsed
-    }
-}
-
-mod day09 {
-    use std::time::{Duration, Instant};
-
-    fn part1(numbers: &[usize]) -> usize {
-        'outer: for i in COUNT..numbers.len() {
-            for x in i - COUNT..i {
-                if numbers[x] > numbers[i] {
-                    continue;
-                }
-
-                for y in x + 1..i {
-                    if numbers[x] + numbers[y] == numbers[i] {
-                        continue 'outer;
-                    }
-                }
-            }
-
-            return numbers[i];
-        }
-
-        panic!();
-    }
-
-    fn part2(numbers: &[usize], part1: usize) -> usize {
-        let mut lower = 0;
-        let mut upper = 0;
-        let mut sum = 0;
-
-        while sum != part1 {
-            while sum < part1 {
-                sum += numbers[upper];
-                upper += 1;
-            }
-
-            while sum > part1 {
-                sum -= numbers[lower];
-                lower += 1;
-            }
-        }
-
-        let slice = &numbers[lower..upper];
-        slice.iter().min().unwrap() + slice.iter().max().unwrap()
-    }
-
-    const COUNT: usize = 25;
-    pub fn run(print: bool) -> Duration {
-        let input = std::fs::read_to_string("../inputs/09").unwrap();
-        let instant = Instant::now();
-
-        let numbers: Vec<usize> = input.split('\n').flat_map(str::parse).collect();
-        let part1 = part1(&numbers);
-        let part2 = part2(&numbers, part1);
-
-        if print {
-            dbg!(part1, part2);
-        }
-
-        instant.elapsed()
-    }
-}
-
-mod day10 {
-    use std::time::Duration;
-
-    pub fn run(_: bool) -> Duration {
-        Duration::new(0, 0)
-    }
-}
-
-mod day11 {
-    use std::time::Duration;
-
-    pub fn run(_: bool) -> Duration {
-        Duration::new(0, 0)
-    }
-}
-
-mod day12 {
-    use std::time::Duration;
-
-    pub fn run(_: bool) -> Duration {
-        Duration::new(0, 0)
-    }
-}
-
-mod day13 {
-    use std::time::Duration;
-
-    pub fn run(_: bool) -> Duration {
-        Duration::new(0, 0)
-    }
-}
-
-mod day14 {
-    use std::time::Duration;
-
-    pub fn run(_: bool) -> Duration {
-        Duration::new(0, 0)
-    }
-}
-
-mod day15 {
-    use std::time::{Duration, Instant};
-
-    const END: usize = 30_000_000;
-    pub fn run(print: bool) -> Duration {
-        let input: Vec<usize> = "0,1,5,10,3,12,19"
-            .split(",")
-            .map(|i| i.parse().unwrap())
-            .collect();
-        let instant = Instant::now();
-
-        let mut history = vec![0; END];
-        let mut last = input[0];
-        for turn in 0..input.len() {
-            history[last] = turn;
-            last = input[turn];
-        }
-
-        for turn in input.len()..2020 {
-            let stored = history[last];
-            history[last] = turn;
-            last = if stored == 0 { 0 } else { turn - stored };
-        }
-        if print {
-            println!("Part 1: {}", last);
-        }
-
-        for turn in 2020..END {
-            let stored = history[last];
-            history[last] = turn;
-            last = if stored == 0 { 0 } else { turn - stored };
-        }
-        if print {
-            println!("Part 2: {}", last);
-        }
-
-        instant.elapsed()
-    }
-}
-
-mod day16 {
-    use std::fmt;
-    use std::time::{Duration, Instant};
-
-    type Ticket = Vec<usize>;
-
-    #[derive(PartialEq, Eq, Hash)]
-    struct Range {
-        from: usize,
-        to: usize,
-    }
-
-    impl fmt::Debug for Range {
-        fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-            f.write_fmt(format_args!("{} - {}", self.from, self.to))
-        }
-    }
-    impl Range {
-        fn from(s: &str) -> Self {
-            let mut range = s.split("-");
-            Self {
-                from: range.next().unwrap().parse().unwrap(),
-                to: range.next().unwrap().parse().unwrap(),
-            }
-        }
-
-        fn contains(&self, i: usize) -> bool {
-            i >= self.from && i <= self.to
-        }
-    }
-
-    #[derive(Debug, PartialEq, Eq, Hash)]
-    struct Rule {
-        name: String,
-        ranges: (Range, Range),
-    }
-
-    impl Rule {
-        fn validate(&self, i: usize) -> bool {
-            let (a, b) = &self.ranges;
-            a.contains(i) || b.contains(i)
-        }
-    }
-
-    pub fn run(print: bool) -> Duration {
-        let input = std::fs::read_to_string("../inputs/16").unwrap();
-        let instant = Instant::now();
-
-        let mut lines = input.lines();
-        let mut rules = Vec::new();
-        while let Some(line) = lines.next() {
-            let mut colon_split = line.split(": ");
-            let name = colon_split.next().unwrap().to_string();
-            if name.is_empty() {
-                break;
-            }
-
-            let mut ranges = colon_split.next().unwrap().split(" or ");
-
-            rules.push(Rule {
-                name,
-                ranges: (
-                    Range::from(ranges.next().unwrap()),
-                    Range::from(ranges.next().unwrap()),
-                ),
-            });
-        }
-
-        lines.next(); // "your ticket:"
-
-        let your_ticket: Ticket = lines
-            .next()
-            .unwrap()
-            .split(",")
-            .map(|s| s.parse().unwrap())
-            .collect();
-
-        lines.next(); // ""
-        lines.next(); // "nearby tickets:"
-
-        let mut nearby_tickets: Vec<Ticket> = Vec::new();
-        while let Some(line) = lines.next() {
-            nearby_tickets.push(line.split(",").map(|s| s.parse().unwrap()).collect());
-        }
-
-        let mut part1 = 0;
-        let mut valid_tickets = Vec::new();
-        for ticket in &nearby_tickets {
-            let mut valid = true;
-            for &field in ticket {
-                let rule = rules.iter().find(|rule| rule.validate(field));
-                if rule.is_none() {
-                    valid = false;
-                    part1 += field;
-                }
-            }
-
-            if valid {
-                valid_tickets.push(ticket);
-            }
-        }
-
-        if print {
-            dbg!(part1);
-        }
-
-        let mut field_possibilities: Vec<_> = (0..your_ticket.len())
-            .map(|_| (0..rules.len()).collect::<Vec<_>>())
-            .collect();
-
-        for ticket in valid_tickets {
-            for (&field, possibilities) in ticket.iter().zip(field_possibilities.iter_mut()) {
-                possibilities
-                    .iter()
-                    .position(|&rule_i| !rules[rule_i].validate(field))
-                    .map(|i| possibilities.remove(i));
-            }
-        }
-
-        let mut part2 = 1;
-        loop {
-            let field_possibility = field_possibilities
-                .iter()
-                .enumerate()
-                .find(|(_, fp)| fp.len() == 1);
-
-            let (i, possibility) = match field_possibility {
-                Some((i, v)) => (i, v[0]),
-                None => break,
-            };
-
-            for fp in field_possibilities.iter_mut() {
-                fp.iter()
-                    .position(|&i| i == possibility)
-                    .map(|i| fp.remove(i));
-            }
-
-            let rule = &rules[possibility].name;
-            if rule.starts_with("de") {
-                part2 *= your_ticket[i];
-            }
-        }
-
-        if print {
-            dbg!(part2);
-        }
-
-        instant.elapsed()
-    }
-}
-
-mod day17 {
-    use std::time::Duration;
-
-    pub fn run(_print: bool) -> Duration {
-        Duration::new(0, 0)
-    }
-}
-
-mod day18 {
-    use std::time::Duration;
-
-    pub fn run(_print: bool) -> Duration {
-        Duration::new(0, 0)
-    }
-}
-
-mod day19 {
-    use std::collections::BTreeMap as HashMap;
-    use std::fs::File;
-    use std::io::{BufWriter, Write};
-    use std::time::{Duration, Instant};
-
-    #[derive(Debug)]
-    enum Rhs {
-        Terminal(char),
-        Variables(Vec<Vec<usize>>),
-    }
-
-    type Rules = HashMap<usize, Rhs>;
-
-    fn parse(input: &str) -> Option<(Rules, Vec<&str>)> {
-        let mut rules = HashMap::new();
-        let mut messages = Vec::new();
-        let mut parsing_rules = true;
-        for line in input.lines() {
-            let trim = line.trim();
-            if trim.is_empty() {
-                parsing_rules = false;
-                continue;
-            }
-
-            if parsing_rules {
-                let mut split = trim.split(": ");
-                let lhs: usize = split.next()?.parse().ok()?;
-
-                let terms = split.next()?;
-                let rhs = if terms.starts_with('"') {
-                    Rhs::Terminal(terms.chars().nth(1)?)
-                } else {
-                    Rhs::Variables(
-                        terms
-                            .split(" | ")
-                            .map(|t| t.split(" ").flat_map(str::parse).collect())
-                            .collect(),
-                    )
-                };
-
-                rules.insert(lhs, rhs);
-            } else {
-                messages.push(trim);
-            }
-        }
-
-        Some((rules, messages))
-    }
-
-    fn generate(rules: &Rules, messages: &Vec<&str>, filename: &str) -> std::io::Result<()> {
-        let write_file = File::create(filename)?;
-        let mut w = BufWriter::new(&write_file);
-
-        writeln!(&mut w, "from typing import Tuple")?;
-        writeln!(&mut w)?;
-
-        for (i, rule) in rules.iter() {
-            writeln!(&mut w, "def rule_{}(s):", i)?;
-            writeln!(&mut w, "    if s != '':")?;
-
-            match rule {
-                Rhs::Terminal(terminal) => {
-                    writeln!(&mut w, "        if s[0] == '{}':", terminal)?;
-                    writeln!(&mut w, "            yield s[1:]")?;
-                }
-
-                Rhs::Variables(variables) => {
-                    for term in variables {
-                        for (j, rule) in term.iter().enumerate() {
-                            if j == 0 {
-                                writeln!(&mut w, "        v{} = rule_{}(s)", j, rule)?;
-                            } else {
-                                writeln!(
-                                    &mut w,
-                                    "        v{} = (out for inp in v{} for out in rule_{}(inp))",
-                                    j,
-                                    j - 1,
-                                    rule,
-                                )?;
-                            }
-                        }
-                        writeln!(&mut w, "        yield from v{}", term.len() - 1)?;
-                        writeln!(&mut w)?;
-                    }
-                }
-            }
-
-            writeln!(&mut w)?;
-        }
-        writeln!(&mut w, "def validate(s):")?;
-        writeln!(&mut w, "    return any(x == '' for x in rule_0(s))")?;
-
-        writeln!(&mut w)?;
-        writeln!(&mut w, "if __name__ == '__main__':")?;
-        writeln!(&mut w, "    result = 0")?;
-        for message in messages {
-            writeln!(&mut w, "    result += validate('{}')", message)?;
-        }
-        writeln!(&mut w, "    print('Result:', result)")?;
-
-        Ok(())
-    }
-
-    pub fn run(_print: bool) -> Duration {
-        let input = std::fs::read_to_string("../inputs/19").unwrap();
-        let instant = Instant::now();
-
-        let (mut rules, messages) = parse(&input).unwrap();
-        generate(&rules, &messages, "/tmp/day19-1.py").unwrap();
-
-        rules.insert(8, Rhs::Variables(vec![vec![42], vec![42, 8]]));
-        rules.insert(11, Rhs::Variables(vec![vec![42, 31], vec![42, 11, 31]]));
-        generate(&rules, &messages, "/tmp/day19-2.py").unwrap();
-
-        instant.elapsed()
-    }
-}
+mod nop;
+
+mod day01;
+mod day02;
+mod day03;
+mod day04;
+mod day05;
+use nop as day06;
+use nop as day07;
+mod day08;
+mod day09;
+use nop as day10;
+use nop as day11;
+use nop as day12;
+use nop as day13;
+use nop as day14;
+mod day15;
+mod day16;
+use nop as day17;
+use nop as day18;
+mod day19;
+use nop as day20;
 
 fn main() {
     let days = [
@@ -825,6 +44,7 @@ fn main() {
         day17::run,
         day18::run,
         day19::run,
+        day20::run,
     ];
 
     if let Some(day) = std::env::args().nth(1) {
diff --git a/rust/src/nop.rs b/rust/src/nop.rs
new file mode 100644
index 0000000..bd5391c
--- /dev/null
+++ b/rust/src/nop.rs
@@ -0,0 +1,5 @@
+use std::time::Duration;
+
+pub fn run(_: bool) -> Duration {
+    Duration::new(0, 0)
+}