day01 both

src/lib.rs

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+pub mod tasks;
+pub mod utils;

src/main.rs

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+fn main() {
+    aoc_2018::tasks::day01::task1();
+    aoc_2018::tasks::day01::task2();
+}

src/tasks/day01.rs

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+use std::collections::HashSet;
+use utils;
+
+pub fn task1() {
+    let contents = utils::read_file("input/day01.txt");
+
+    let mut frequency = 0;
+    for line in contents.split_whitespace() {
+        let number: i32 = line.parse().unwrap();
+        frequency += number;
+    }
+
+    println!("Result: {}", frequency);
+}
+
+pub fn task2() {
+    let contents = utils::read_file("input/day01.txt");
+
+    let mut seen = HashSet::new();
+
+    let mut frequency = 0;
+    seen.insert(frequency);
+    let changes: Vec<i32> = contents.lines().map(|line| line.parse().unwrap()).collect();
+
+    loop {
+        for number in changes.iter() {
+            frequency += number;
+            if seen.contains(&frequency) {
+                println!("{} was there already!", frequency);
+                return;
+            }
+
+            seen.insert(frequency);
+        }
+    }
+}

src/tasks/mod.rs

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+pub mod day01;

src/utils.rs

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+use std::fs::File;
+use std::io::prelude::*;
+
+pub fn read_file(path: &str) -> String {
+    let mut f = File::open(path).expect(&format!("file '{}' not found", path));
+
+    let mut contents = String::new();
+    f.read_to_string(&mut contents)
+        .expect("something went wrong reading the file");
+    contents
+}