Complete day 4.1

day-4/.gitignore

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+/target/

day-4/Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+[[package]]
+name = "day-4"
+version = "0.1.0"
+dependencies = [
+ "indoc",
+]
+
+[[package]]
+name = "indoc"
+version = "0.3.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "47741a8bc60fb26eb8d6e0238bbb26d8575ff623fdc97b1a2c00c050b9684ed8"
+dependencies = [
+ "indoc-impl",
+ "proc-macro-hack",
+]
+
+[[package]]
+name = "indoc-impl"
+version = "0.3.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ce046d161f000fffde5f432a0d034d0341dc152643b2598ed5bfce44c4f3a8f0"
+dependencies = [
+ "proc-macro-hack",
+ "proc-macro2",
+ "quote",
+ "syn",
+ "unindent",
+]
+
+[[package]]
+name = "proc-macro-hack"
+version = "0.5.19"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dbf0c48bc1d91375ae5c3cd81e3722dff1abcf81a30960240640d223f59fe0e5"
+
+[[package]]
+name = "proc-macro2"
+version = "1.0.24"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1e0704ee1a7e00d7bb417d0770ea303c1bccbabf0ef1667dae92b5967f5f8a71"
+dependencies = [
+ "unicode-xid",
+]
+
+[[package]]
+name = "quote"
+version = "1.0.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "aa563d17ecb180e500da1cfd2b028310ac758de548efdd203e18f283af693f37"
+dependencies = [
+ "proc-macro2",
+]
+
+[[package]]
+name = "syn"
+version = "1.0.53"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8833e20724c24de12bbaba5ad230ea61c3eafb05b881c7c9d3cfe8638b187e68"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-xid",
+]
+
+[[package]]
+name = "unicode-xid"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f7fe0bb3479651439c9112f72b6c505038574c9fbb575ed1bf3b797fa39dd564"
+
+[[package]]
+name = "unindent"
+version = "0.1.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f14ee04d9415b52b3aeab06258a3f07093182b88ba0f9b8d203f211a7a7d41c7"

day-4/Cargo.toml

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+[package]
+name = "day-4"
+version = "0.1.0"
+authors = ["Tristan Daniël Maat <tm@tlater.net>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+indoc = "0.3"

day-4/src/main.rs

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+use std::collections::HashMap;
+use std::fs;
+
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let input = fs::read_to_string("input")?;
+    let passports = parse_passports(&input)?;
+    println!("{}", validate_passports(&passports));
+
+    Ok(())
+}
+
+fn parse_passports(input: &str) -> Result<Vec<HashMap<&str, &str>>, &str> {
+    input
+        .split("\n\n")
+        .map(|passport| {
+            passport
+                .trim()
+                .split(|c| c == ' ' || c == '\n')
+                .map(|field| {
+                    let split = field
+                        .find(':')
+                        .ok_or("Invalid passport entry; no separator")?;
+                    let item = field.split_at(split);
+
+                    let key = item.0;
+                    let value = item
+                        .1
+                        .strip_prefix(":")
+                        .expect("We've already checked the separator exists");
+
+                    Ok((key, value))
+                })
+                .collect()
+        })
+        .collect()
+}
+
+fn validate_passports(passports: &Vec<HashMap<&str, &str>>) -> usize {
+    let required_fields = ["byr", "iyr", "eyr", "hgt", "hcl", "ecl", "pid"];
+
+    passports
+        .iter()
+        .filter(|passport| {
+            required_fields
+                .iter()
+                .all(|field| passport.contains_key(field))
+        })
+        .count()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use indoc::indoc;
+
+    #[test]
+    fn test_simple() -> Result<(), String> {
+        let example = indoc!(
+            "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
+             "
+        );
+
+        let passports = parse_passports(example)?;
+        assert_eq!(validate_passports(&passports), 2);
+
+        Ok(())
+    }
+}