2020: day04: part 1

aoc2020/src/day04.rs

@@ -0,0 +1,111 @@
+use std::collections::HashMap;
+use std::fmt::Write;
+use std::str::FromStr;
+
+const INPUT: &str = include_str!("../input/day04.txt");
+
+pub fn run() -> aoc::Result<String> {
+    let mut res = String::with_capacity(128);
+
+    writeln!(res, "part 1: {}", part1(INPUT)?)?;
+
+    Ok(res)
+}
+
+fn get_passports(input: &str) -> aoc::Result<Vec<Passport>> {
+    let mut passports: Vec<Passport> = Vec::new();
+
+    let mut passport = String::new();
+    for line in input.lines() {
+        if line.is_empty() {
+            passports.push(passport.parse()?);
+            passport.clear();
+        } else {
+            passport.push('\n');
+            passport.push_str(line);
+        }
+    }
+
+    if !passport.is_empty() {
+        passports.push(passport.parse()?);
+    }
+
+    Ok(passports)
+}
+
+fn part1(input: &str) -> aoc::Result<usize> {
+    let passports = get_passports(input)?;
+
+    Ok(passports.iter().filter(|p| p.has_valid_fields()).count())
+}
+
+#[derive(Debug)]
+struct Passport {
+    byr: Option<String>,
+    iyr: Option<String>,
+    eyr: Option<String>,
+    hgt: Option<String>,
+    hcl: Option<String>,
+    ecl: Option<String>,
+    pid: Option<String>,
+    #[allow(dead_code)]
+    cid: Option<String>,
+}
+
+impl Passport {
+    fn has_valid_fields(&self) -> bool {
+        self.byr.is_some()
+            && self.iyr.is_some()
+            && self.eyr.is_some()
+            && self.hgt.is_some()
+            && self.hcl.is_some()
+            && self.ecl.is_some()
+            && self.pid.is_some()
+    }
+}
+
+impl FromStr for Passport {
+    type Err = aoc::Error;
+
+    fn from_str(s: &str) -> aoc::Result<Self> {
+        let mut fields: HashMap<&str, String> = s
+            .split_whitespace()
+            .map(|f| {
+                let mut it = f.split(':');
+
+                let key = it.next().unwrap();
+                let value = it.next().unwrap().to_string();
+
+                (key, value)
+            })
+            .collect();
+
+        Ok(Passport {
+            byr: fields.remove("byr"),
+            iyr: fields.remove("iyr"),
+            eyr: fields.remove("eyr"),
+            hgt: fields.remove("hgt"),
+            hcl: fields.remove("hcl"),
+            ecl: fields.remove("ecl"),
+            pid: fields.remove("pid"),
+            cid: fields.remove("cid"),
+        })
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    static PROVIDED: &'static str = include_str!("../input/day04_provided.txt");
+
+    #[test]
+    fn part1_provided() {
+        assert_eq!(part1(PROVIDED).unwrap(), 2);
+    }
+
+    #[test]
+    fn part1_real() {
+        assert_eq!(part1(INPUT).unwrap(), 192);
+    }
+}

aoc2020/src/lib.rs

@@ -1,3 +1,4 @@
 pub mod day01;
 pub mod day02;
 pub mod day03;
+pub mod day04;

aoc2020/src/main.rs

@@ -4,9 +4,10 @@ use aoc::Result;
 use aoc2020::day01;
 use aoc2020::day02;
 use aoc2020::day03;
+use aoc2020::day04;
 
 fn main() -> Result<()> {
-    let days: &[DayFunc] = &[day01::run, day02::run, day03::run];
+    let days: &[DayFunc] = &[day01::run, day02::run, day03::run, day04::run];
 
     aoc::run(days)
 }