Challenge one

.gitignore

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+/target
+**/*.rs.bk

Cargo.lock

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+[[package]]
+name = "AoC-2018"
+version = "0.1.0"
+

Cargo.toml

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+[package]
+name = "AoC-2018"
+version = "0.1.0"
+authors = ["Kevin Cotugno <kevin@kevincotugno.com>"]
+
+[[bin]]
+name = "AoC-2018"
+path = "src/bin/main.rs"
+
+[lib]
+name = "aoc"
+path = "src/aoc/lib.rs"
+
+[dependencies]

src/aoc/c01.rs

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+use std::collections::HashSet;
+
+pub fn run(input: &[String], part: u8) -> String {
+    let encoded: Vec<_> = input.iter().map(|i| i.parse::<i32>().unwrap()).collect();
+    match part {
+        1 => c_01_1(&encoded),
+        2 => c_01_2(&encoded),
+        _ => panic!("unknown part"),
+    }.to_string()
+}
+
+fn c_01_1(input: &[i32]) -> i32 {
+    let mut n = 0;
+    for x in input {
+        n += x;
+    }
+    n
+}
+
+fn c_01_2(input: &[i32]) -> i32 {
+    let mut freq = HashSet::new();
+    freq.insert(0);
+    let mut n = 0;
+    loop {
+        for x in input {
+            n += x;
+            if freq.contains(&n) {
+                return n;
+            } else {
+                freq.insert(n);
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::collections::HashMap;
+
+    #[test]
+    fn c_01_1_examples() -> Result<(), String> {
+        let mut examples: HashMap<&[i32], i32> = HashMap::new();
+        examples.insert(&[1, 1, 1], 3);
+        examples.insert(&[1, 1, -2], 0);
+        examples.insert(&[-1, -2, -3], -6);
+
+        for (input, out) in examples.iter() {
+            let actual = c_01_1(input);
+            if &actual != out {
+                return Err(format!("Got: {}, Want: {}", actual, out));
+            }
+        }
+
+        Ok(())
+    }
+
+    #[test]
+    fn c_01_2_examples() -> Result<(), String> {
+        let mut examples: HashMap<&[i32], i32> = HashMap::new();
+        examples.insert(&[1, -1], 0);
+        examples.insert(&[3, 3, 4, -2, -4], 10);
+        examples.insert(&[-6, 3, 8, 5, -6], 5);
+        examples.insert(&[7, 7, -2, -7, -4], 14);
+
+        for (input, out) in examples.iter() {
+            let actual = c_01_2(input);
+            if &actual != out {
+                return Err(format!("Got: {}, Want: {}", actual, out));
+            }
+        }
+
+        Ok(())
+    }
+}

src/aoc/lib.rs

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+mod c01;
+
+pub fn run(input: &[String], challenge: u8, part: u8) -> String {
+    match challenge {
+        1 => c01::run(input, part),
+        _ => panic!("challenge not implemented"),
+    }
+}

src/bin/main.rs

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+extern crate aoc;
+
+use std::env;
+use std::fs;
+
+fn main() {
+    let mut args = env::args();
+    if args.len() < 3 {
+        eprintln!("not enough args");
+    }
+
+    args.next();
+    let challenge: u8 = args.next().unwrap().parse().unwrap();
+    let part: u8 = args.next().unwrap().parse().unwrap();
+
+    let lines: Vec<String> = fs::read_to_string(format!("input/{:02}.txt", challenge))
+        .unwrap()
+        .lines()
+        .filter(|v| !v.trim().is_empty())
+        .map(|v| v.to_string())
+        .collect();
+
+    println!("{}", aoc::run(&lines, challenge, part));
+}