day 2

Cargo.toml

@@ -7,3 +7,4 @@ edition = "2018"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+regex = "1"

src/lib.rs

@@ -1,11 +1,13 @@
-
+use std::fs;
 use std::fs::File;
-use std::io::{prelude::*, BufReader, Error};
+use std::io::{prelude::*, BufReader};
+use std::error::Error;
+use regex::Regex;
 
 
 
-pub fn aoc_01_01(filename: &str) -> Result<(), Error> {
 
+pub fn aoc_01_both(filename: &str) -> Result<(), Box<dyn Error>> {
     let file = File::open(filename).expect("No file");
     let br = BufReader::new(file);
     let mut v: Vec<i64> = vec![];
@@ -35,5 +37,54 @@ pub fn aoc_01_01(filename: &str) -> Result<(), Error> {
     }
 
     return Ok(());
+}
 
+pub fn aoc_02(filename: &str) -> Result<(), Box<dyn Error>> {
+    let contents = fs::read_to_string(filename)?;
+
+
+    let pairs: Vec<Vec<String>> = contents.lines().map(|line| {
+        line.split(":").map(|s| String::from(s)).collect()
+    }).collect();
+
+    aoc_02_01(&pairs).unwrap();
+    aoc_02_02(&pairs).unwrap();
+    Ok(())
+}
+
+fn aoc_02_01(pairs: &Vec<Vec<String>>) -> Result<(), Box<dyn Error>> {
+    let mut valid = 0;
+    let rules_re = Regex::new(r"(\d*)-(\d*) ([a-z])").unwrap();
+    for i in 0..pairs.len() {
+        let rule = rules_re.captures(&pairs[i][0]).unwrap();
+        let min = rule[1].parse::<usize>().unwrap();
+        let max = rule[2].parse::<usize>().unwrap();
+        let matches: usize = pairs[i][1].matches(&rule[3]).count();
+        if matches >= min && matches <= max {
+            valid += 1;
+        }
+    }
+
+    println!("2_1 had {}/{} valid passwords", valid, pairs.len());
+    return Ok(());
+}
+
+fn aoc_02_02(pairs: &Vec<Vec<String>>) -> Result<(), Box<dyn Error>> {
+    let mut valid = 0;
+    let rules_re = Regex::new(r"(\d*)-(\d*) ([a-z])").unwrap();
+    for i in 0..pairs.len() {
+        let rule = rules_re.captures(&pairs[i][0]).unwrap();
+        let first = rule[1].parse::<usize>().unwrap();
+        let sec = rule[2].parse::<usize>().unwrap();
+
+        let m1 = pairs[i][1].as_bytes()[first] == rule[3].as_bytes()[0];
+        let m2 = pairs[i][1].as_bytes()[sec] == rule[3].as_bytes()[0];
+        if (m1 || m2) && !(m1 && m2) {
+            valid += 1;
+        }
+
+    }
+
+    println!("2_2 had {}/{} valid passwords", valid, pairs.len());
+    return Ok(());
 }

src/main.rs

@@ -1,8 +1,20 @@
-
+use std::env;
-
 
 fn main() {
-    //let filename = env::args().nth(1).expect("input filename required");
+    let day = match env::args().nth(1) {
+        Some(arg) => arg.parse().unwrap(),
+        None => 1
+    };
+
+    let result = match day {
+        1 => advent_of_code::aoc_01_both("./inputs/01-01.txt"),
+        2 => advent_of_code::aoc_02("./inputs/02-01.txt"),
+        _ => Err(format!("unsupported day {}", day).into()),
+    };
+
+    match result {
+        Ok(_) => (),
+        Err(e) => println!("Error executing day {}: {}", day, e),
+    }
 
-    advent_of_code::aoc_01_01("./inputs/01-01.txt");
 }