init

.gitignore

@@ -0,0 +1,2 @@
+/target
+/input

Cargo.lock

@@ -0,0 +1,178 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "advent_of_code_2020"
+version = "0.1.0"
+dependencies = [
+ "aoc-runner",
+ "aoc-runner-derive",
+ "itertools",
+ "strum",
+ "strum_macros",
+]
+
+[[package]]
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+
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+dependencies = [
+ "aoc-runner-internal",
+ "proc-macro2",
+ "quote",
+ "syn 1.0.109",
+]
+
+[[package]]
+name = "aoc-runner-internal"
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+]
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+
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+ "quote",
+ "syn 2.0.42",
+]
+
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+ "ryu",
+ "serde",
+]
+
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+
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+dependencies = [
+ "heck",
+ "proc-macro2",
+ "quote",
+ "rustversion",
+ "syn 2.0.42",
+]
+
+[[package]]
+name = "syn"
+version = "1.0.109"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "72b64191b275b66ffe2469e8af2c1cfe3bafa67b529ead792a6d0160888b4237"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
+[[package]]
+name = "syn"
+version = "2.0.42"
+source = "registry+https://github.com/rust-lang/crates.io-index"
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+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
+[[package]]
+name = "unicode-ident"
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Cargo.toml

@@ -0,0 +1,16 @@
+[package]
+name = "advent_of_code_2020"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[lib]
+bench = false
+
+[dependencies]
+aoc-runner = "0.3.0"
+aoc-runner-derive = "0.3.0"
+itertools = "0.12.0"
+strum = "0.25.0"
+strum_macros = "0.25"

src/day1.rs

@@ -0,0 +1,46 @@
+use aoc_runner_derive::{aoc, aoc_generator};
+use itertools::Itertools;
+#[aoc_generator(day1)]
+fn parse(input: &str) -> Vec<u64> {
+    input.lines()
+    .map(str::parse::<u64>)
+    .map(Result::unwrap)
+    .collect_vec()
+}
+
+#[aoc(day1, part1)]
+fn part1(input: &Vec<u64>) -> u64 {
+    input.iter().combinations(2)
+        .find(|x| x.iter().cloned().sum::<u64>() == 2020)
+        .map(|x| x.iter().cloned().product()).unwrap()
+}
+
+#[aoc(day1, part2)]
+fn part2(input: &Vec<u64>) -> u64 {
+    input.iter().combinations(3)
+        .find(|x| x.iter().cloned().sum::<u64>() == 2020)
+        .map(|x| x.iter().cloned().product()).unwrap()
+}
+
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+const EX: &str = r"1721
+979
+366
+299
+675
+1456";
+
+    #[test]
+    fn part1_example() {
+        assert_eq!(part1(&parse(EX)), 514579);
+    }
+
+    #[test]
+    fn part2_example() {
+        assert_eq!(part2(&parse(EX)), 241861950);
+    }
+}

src/day2.rs

@@ -0,0 +1,75 @@
+use aoc_runner_derive::{aoc, aoc_generator};
+
+#[derive(Debug)]
+struct Policy {
+    min: u32,
+    max: u32,
+    match_char: char,
+}
+
+#[aoc_generator(day2)]
+fn parse(input: &str) -> Vec<(Policy, String)> {
+    let input = input.lines().map(|line| {
+        let line = line.split(": ").collect::<Vec<_>>();
+
+        let policy = line[0].split(' ').collect::<Vec<_>>();
+        let min = policy[0][0..policy[0].find('-').unwrap()].parse::<u32>().unwrap();
+        let max = policy[0][policy[0].find('-').unwrap() + 1..].parse::<u32>().unwrap();
+        let match_char = policy[1].chars().next().unwrap();
+        (Policy {min, max, match_char}, line[1].to_string())
+    }).collect::<Vec<_>>();
+
+    input
+}
+
+#[aoc(day2, part1)]
+fn part1(passwords: &Vec<(Policy, String)>) -> u32 {
+    let mut valid_count = 0;
+    for (Policy {min, max, match_char}, password) in passwords {
+        let mut count = 0;
+        for char in password.chars() {
+            if char == *match_char {
+                count += 1;
+            }
+        }
+        if count >= *min && count <= *max {
+            valid_count += 1;
+        }
+    }
+
+    valid_count
+}
+
+#[aoc(day2, part2)]
+fn part2(passwords: &Vec<(Policy, String)>) -> u32 {
+    let mut valid_count = 0;
+    for (Policy {min, max, match_char}, password) in passwords {
+        let first = password.chars().collect::<Vec<_>>()[(*min - 1) as usize] == *match_char;
+        let second = password.chars().collect::<Vec<_>>()[(*max - 1) as usize] == *match_char;
+        if first ^ second {
+            valid_count += 1;
+        }
+    }
+
+    valid_count
+}
+
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const EX: &str = r"1-3 a: abcde
+1-3 b: cdefg
+2-9 c: ccccccccc";
+
+    #[test]
+    fn part1_example() {
+        assert_eq!(part1(&parse(EX)), 2);
+    }
+
+    #[test]
+    fn part2_example() {
+        assert_eq!(part2(&parse(EX)), 1);
+    }
+}

src/day3.rs

@@ -0,0 +1,64 @@
+use aoc_runner_derive::{aoc, aoc_generator};
+
+#[aoc_generator(day3)]
+fn parse(input: &str) -> Vec<Vec<char>> {
+    let input = input.lines().map(|line| {
+        line.chars().collect::<Vec<_>>()
+    }).collect::<Vec<_>>();
+
+    input
+}
+
+#[aoc(day3, part1)]
+fn part1(input: &Vec<Vec<char>>) -> u64 {
+    count_trees(1, 3, input)
+}
+
+#[aoc(day3, part2)]
+fn part2(input: &Vec<Vec<char>>) -> u64 {
+    vec![(1,1), (1,3), (1,5), (1,7), (2,1)].iter()
+        .map(|(rise, run)| {
+            count_trees(*rise, *run, input)
+        }).product()
+}
+
+fn count_trees(rise: usize, run: usize, input: &Vec<Vec<char>>) -> u64 {
+    let mut x = 0;
+    let mut tree_count = 0;
+
+    for y in (rise..input.len()).step_by(rise) {
+        x += run;
+        if input[y][x % input[0].len()] == '#' {
+            tree_count += 1;
+        }
+    }
+    tree_count
+}
+
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+const EX: &str = r"..##.......
+#...#...#..
+.#....#..#.
+..#.#...#.#
+.#...##..#.
+..#.##.....
+.#.#.#....#
+.#........#
+#.##...#...
+#...##....#
+.#..#...#.#";
+
+    #[test]
+    fn part1_example() {
+        assert_eq!(part1(&parse(EX)), 7);
+    }
+
+    #[test]
+    fn part2_example() {
+        assert_eq!(part2(&parse(EX)), 336);
+    }
+}

src/day4.rs

@@ -0,0 +1,202 @@
+use aoc_runner_derive::{aoc, aoc_generator};
+use strum::IntoEnumIterator;
+use strum_macros::EnumIter;
+
+#[derive(Debug, EnumIter, PartialEq, Clone, Copy)]
+enum IDField {
+    BirthYear,
+    IssueYear,
+    ExpirationYear,
+    Height,
+    HairColor,
+    EyeColor,
+    PassportID,
+    CountryID
+}
+
+impl From<&str> for IDField {
+    fn from(value: &str) -> Self {
+        match &*value {
+            "byr" => Self::BirthYear,
+            "iyr" => Self::IssueYear,
+            "eyr" => Self::ExpirationYear,
+            "hgt" => Self::Height,
+            "hcl" => Self::HairColor,
+            "ecl" => Self::EyeColor,
+            "pid" => Self::PassportID,
+            "cid" => Self::CountryID,
+            _ => unreachable!()
+        }
+    }
+}
+
+impl IDField {
+    fn validate(&self, val: &str) -> bool {
+        match self {
+            IDField::BirthYear => {
+                if val.len() == 4 {
+                    if let Ok(num) = val.parse::<u32>() {
+                        if num >= 1920 && num <= 2002 {
+                            return true;
+                        }
+                    }
+                }
+                false
+            },
+            IDField::IssueYear => {
+                if val.len() == 4 {
+                    if let Ok(num) = val.parse::<u32>() {
+                        if num >= 2010 && num <= 2020 {
+                            return true;
+                        }
+                    }
+                }
+                false
+            },
+            IDField::ExpirationYear => {
+                if val.len() == 4 {
+                    if let Ok(num) = val.parse::<u32>() {
+                        if num >= 2020 && num <= 2030 {
+                            return true;
+                        }
+                    }
+                }
+                false
+            },
+            IDField::Height => {
+                if let Some(idx) = val.find("cm") {
+                    if let Ok(num) = val[0..idx].parse::<u32>() {
+                        if num >= 150 && num <= 193 {
+                            return true;
+                        }
+                    }
+                } else if let Some(idx) = val.find("in")  {
+                    if let Ok(num) = val[0..idx].parse::<u32>() {
+                        if num >= 59 && num <= 76 {
+                            return true;
+                        }
+                    }
+                }
+                false
+            },
+            IDField::HairColor => {
+                if val.chars().next().unwrap() == '#' {
+                    return val[1..].chars().all(|char| char.is_ascii_hexdigit())
+                }
+
+                false
+            },
+            IDField::EyeColor => {
+                match val {
+                    "amb" | "blu" | "brn" | "gry" | "grn" | "hzl" | "oth" => true,
+                    _ => false
+                }
+            },
+            IDField::PassportID => {
+                val.len() == 9 && val.chars().all(char::is_numeric)
+            },
+            IDField::CountryID => true,
+        }
+    }
+}
+
+
+#[aoc_generator(day4)]
+fn parse(input: &str) -> Vec<Vec<(IDField, String)>> {
+    let input = input.split("\n\n")
+        .map(str::split_ascii_whitespace)
+        .map(|line| {
+            line.map(|field_str| {
+                let colon = field_str.find(':').unwrap();
+                (field_str[0..colon].into(), field_str[colon + 1..].to_string())
+            }).collect::<Vec<_>>()
+        }).collect::<Vec<_>>();
+
+    input
+}
+
+#[aoc(day4, part1)]
+fn part1(input: &Vec<Vec<(IDField, String)>>) -> u32 {
+    input.iter()
+    .map(|passport| {
+        let passport = passport.iter().map(|(field, _)| *field).collect::<Vec<_>>();
+        IDField::iter().all(|x| {
+            if x == IDField::CountryID {
+                return true
+            }
+            passport.contains(&x)
+        })
+    }).filter(|x| *x).count() as u32
+}
+
+#[aoc(day4, part2)]
+fn part2(input: &Vec<Vec<(IDField, String)>>) -> u32 {
+    input.iter().map(|passport| {
+        IDField::iter().all(|x| {
+            if x == IDField::CountryID {
+                return true
+            }
+            if let Some((_, val)) = passport.iter().find(|(field, _)| field == &x ) {
+                return x.validate(&val)
+            }
+            false
+        })
+    }).filter(|x| *x).count() as u32
+}
+
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+const EX: &str = r"ecl:gry pid:860033327 eyr:2020 hcl:#fffffd
+byr:1937 iyr:2017 cid:147 hgt:183cm
+
+iyr:2013 ecl:amb cid:350 eyr:2023 pid:028048884
+hcl:#cfa07d byr:1929
+
+hcl:#ae17e1 iyr:2013
+eyr:2024
+ecl:brn pid:760753108 byr:1931
+hgt:179cm
+
+hcl:#cfa07d eyr:2025 pid:166559648
+iyr:2011 ecl:brn hgt:59in";
+
+const EX_2: &str = r"eyr:1972 cid:100
+hcl:#18171d ecl:amb hgt:170 pid:186cm iyr:2018 byr:1926
+
+iyr:2019
+hcl:#602927 eyr:1967 hgt:170cm
+ecl:grn pid:012533040 byr:1946
+
+hcl:dab227 iyr:2012
+ecl:brn hgt:182cm pid:021572410 eyr:2020 byr:1992 cid:277
+
+hgt:59cm ecl:zzz
+eyr:2038 hcl:74454a iyr:2023
+pid:3556412378 byr:2007
+
+pid:087499704 hgt:74in ecl:grn iyr:2012 eyr:2030 byr:1980
+hcl:#623a2f
+
+eyr:2029 ecl:blu cid:129 byr:1989
+iyr:2014 pid:896056539 hcl:#a97842 hgt:165cm
+
+hcl:#888785
+hgt:164cm byr:2001 iyr:2015 cid:88
+pid:545766238 ecl:hzl
+eyr:2022
+
+iyr:2010 hgt:158cm hcl:#b6652a ecl:blu byr:1944 eyr:2021 pid:093154719";
+
+    #[test]
+    fn part1_example() {
+        assert_eq!(part1(&parse(EX)), 2);
+    }
+
+    #[test]
+    fn part2_example() {
+        assert_eq!(part2(&parse(EX_2)), 4);
+    }
+}

src/lib.rs

@@ -0,0 +1,10 @@
+mod day1;
+mod day4;
+mod day3;
+mod day2;
+extern crate aoc_runner;
+
+#[macro_use]
+extern crate aoc_runner_derive;
+
+aoc_lib!{ year = 2020 }

src/main.rs

@@ -0,0 +1,7 @@
+extern crate advent_of_code_2020;
+extern crate aoc_runner_derive;
+extern crate aoc_runner;
+
+use aoc_runner_derive::aoc_main;
+
+aoc_main! { lib = advent_of_code_2020 }