Implement day 1 2018.

We've started.

.travis.yml

@@ -13,4 +13,4 @@ cache: cargo
 
 # Custom directory, for the correct year
 before_script:
-    - cd 2016
+    - cd 2018

2018/src/day01.rs

@@ -0,0 +1,79 @@
+use std::collections::HashSet;
+use std::io;
+use std::io::prelude::*;
+use common;
+
+pub struct Day01 {}
+
+impl Day01 {
+    pub fn new() -> Day01 {
+        Day01 {}
+    }
+}
+
+impl common::Solution for Day01 {
+    fn part1(&mut self, input: &mut io::Read) -> String {
+        let reader = io::BufReader::new(input);
+
+        let sum: i32 = reader.lines()
+            .map(|x| x.unwrap().parse::<i32>().unwrap())
+            .sum();
+
+        format!("{}", sum)
+    }
+
+    fn part2(&mut self, input: &mut io::Read) -> String {
+        let reader = io::BufReader::new(input);
+        let mut freqs = HashSet::new();
+        freqs.insert(0);
+
+        let mut sum = 0;
+        let nums: Vec<i32> = reader.lines()
+            .map(|x| x.unwrap().parse().unwrap())
+            .collect();
+        loop {
+            for amount in &nums {
+                sum += amount;
+                if freqs.contains(&sum) {
+                    return format!("{}", sum);
+                } else {
+                    freqs.insert(sum);
+                }
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use common::Solution;
+
+    #[test]
+    fn samples_part1() {
+        let mut instance = Day01::new();
+        let sample1 = "+1\n+1\n+1";
+        let sample2 = "+1\n+1\n-2";
+        let sample3 = "-1\n-2\n-3";
+
+        assert_eq!("3", instance.part1(&mut sample1.as_bytes()));
+        assert_eq!("0", instance.part1(&mut sample2.as_bytes()));
+        assert_eq!("-6", instance.part1(&mut sample3.as_bytes()));
+    }
+
+    #[test]
+    fn samples_part2() {
+        let mut instance = Day01::new();
+        let sample1 = "+1\n-1";
+        let sample2 = "+3\n+3\n+4\n-2\n-4";
+        let sample3 = "-6\n+3\n+8\n+5\n-6";
+        let sample4 = "+7\n+7\n-2\n-7\n-4";
+
+        assert_eq!("0", instance.part2(&mut sample1.as_bytes()));
+        assert_eq!("10", instance.part2(&mut sample2.as_bytes()));
+        assert_eq!("5", instance.part2(&mut sample3.as_bytes()));
+        assert_eq!("14", instance.part2(&mut sample4.as_bytes()));
+    }
+
+
+}

2018/src/day1.rs

@@ -1,21 +0,0 @@
-use std::io;
-use common;
-
-pub struct Day1 {
-}
-
-impl Day1 {
-    pub fn new() -> Day1 {
-        Day1{}
-    }
-}
-
-impl common::Solution for Day1 {
-    fn part1(&mut self, input: &mut io::Read) -> String {
-        panic!("Not implemented");
-    }
-
-    fn part2(&mut self, input: &mut io::Read) -> String {
-        panic!("Not implemented");
-    }
-}

2018/src/main.rs

@@ -4,14 +4,13 @@ use std::fs;
 use std::io;
 
 pub mod common;
-pub mod day1;
+pub mod day01;
 
-fn get_impl(day: i32) -> Box<common::Solution> {
-    match day {
-        1 => { Box::new(day1::Day1::new()) }
-        _ => {
-            panic!("Unimplemented day {}", day)
-        }
+fn get_impl(day: &str) -> Box<common::Solution> {
+    match day.parse() {
+        Ok(1) => { Box::new(day01::Day01::new()) }
+        Ok(val) => panic!("Unimplemented day {}", val),
+        _ => panic!("Invalid number"),
     }
 }
 
@@ -35,9 +34,7 @@ fn main() {
              .takes_value(true))
         .get_matches();
 
-    let day: i32 = (&matches.value_of("day").unwrap()).parse()
-        .expect("Invalid int");
-    let mut implementation = get_impl(day);
+    let mut implementation = get_impl(matches.value_of("day").unwrap());
     let mut data: Box<io::Read> = match matches.value_of("input") {
         Some(filename) => { Box::new(fs::File::open(filename).unwrap()) }
         None => { Box::new(io::stdin()) }
@@ -59,7 +56,7 @@ mod tests {
         // Verify that we can load all days
         let last_implemented = 1;
         for d in 1..(last_implemented + 1) {
-            get_impl(d);
+            get_impl(&format!("{}", d));
         }
     }
 }