Completed day 1

day1/.gitignore

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

day1/Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+[[package]]
+name = "day1"
+version = "0.1.0"
+

day1/Cargo.toml

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+[package]
+name = "day1"
+version = "0.1.0"
+authors = ["Tyler Hallada <tyler@hallada.net>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

day1/input/input.txt

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+109506
+140405
+139135
+110950
+84296
+123991
+59438
+85647
+81214
+100517
+100910
+57704
+83368
+50777
+85523
+95788
+127699
+138908
+95502
+81703
+67317
+108468
+58394
+72202
+121580
+86908
+72705
+86578
+83714
+114900
+142915
+51332
+69054
+97039
+143539
+61143
+113534
+98335
+58533
+83893
+127138
+50844
+88397
+133591
+83563
+52435
+96342
+109491
+81148
+127397
+86200
+92418
+144842
+120142
+97531
+54449
+91004
+129115
+142487
+68513
+140405
+80111
+139359
+57486
+116973
+135102
+59737
+144040
+95483
+134470
+60473
+113142
+78189
+53845
+124139
+78055
+63791
+99879
+58630
+111233
+80544
+76932
+79644
+116247
+54646
+85217
+110795
+142095
+74492
+93318
+122300
+82755
+147407
+98697
+98105
+132055
+67856
+109731
+75747
+135700

day1/input/test.txt

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+12
+14
+1969
+100756

day1/src/main.rs

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+use std::fs::File;
+use std::io::{self, prelude::*, BufReader};
+
+const INPUT: &str = "input/input.txt";
+
+fn read_masses(filename: &str) -> io::Result<Vec<u32>> {
+    let file = File::open(filename)?;
+    let reader = BufReader::new(file);
+
+    Ok(reader
+        .lines()
+        .map(|mass| mass.unwrap().parse().unwrap())
+        .collect())
+}
+
+fn calculate_fuel_requirement(mass: u32) -> u32 {
+    mass / 3 - 2
+}
+
+fn calculate_fuel_requirement_including_fuel_mass(mass: u32) -> u32 {
+    let mut fuel: i32 = mass as i32 / 3 - 2;
+    let mut total_requirement = 0;
+
+    while fuel > 0 {
+        total_requirement += fuel as u32;
+        fuel = fuel / 3 - 2;
+    }
+
+    total_requirement
+}
+
+fn calculate_fuel_sum(masses: Vec<u32>) -> u32 {
+    let fuel_requirements: Vec<u32> = masses
+        .iter()
+        .map(|mass| calculate_fuel_requirement(*mass))
+        .collect();
+    fuel_requirements.iter().sum()
+}
+
+fn calculate_fuel_sum_including_fuel_mass(masses: Vec<u32>) -> u32 {
+    let fuel_requirements: Vec<u32> = masses
+        .iter()
+        .map(|mass| calculate_fuel_requirement_including_fuel_mass(*mass))
+        .collect();
+    fuel_requirements.iter().sum()
+}
+
+fn solve_part1() -> io::Result<u32> {
+    Ok(calculate_fuel_sum(read_masses(INPUT)?))
+}
+
+fn solve_part2() -> io::Result<u32> {
+    Ok(calculate_fuel_sum_including_fuel_mass(read_masses(INPUT)?))
+}
+
+fn main() -> io::Result<()> {
+    println!("Part 1: {}", solve_part1()?);
+    println!("Part 2: {}", solve_part2()?);
+
+    Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const TEST_INPUT: &str = "input/test.txt";
+
+    #[test]
+    fn reads_masses() {
+        assert_eq!(read_masses(TEST_INPUT).unwrap(), vec![12, 14, 1969, 100756]);
+    }
+
+    #[test]
+    fn calculates_correct_fuel_requirements() {
+        assert_eq!(calculate_fuel_requirement(12), 2);
+        assert_eq!(calculate_fuel_requirement(14), 2);
+        assert_eq!(calculate_fuel_requirement(1969), 654);
+        assert_eq!(calculate_fuel_requirement(100756), 33583);
+    }
+
+    #[test]
+    fn calculates_correct_fuel_requirements_including_fuel_mass() {
+        assert_eq!(calculate_fuel_requirement_including_fuel_mass(14), 2);
+        assert_eq!(calculate_fuel_requirement_including_fuel_mass(1969), 966);
+        assert_eq!(calculate_fuel_requirement_including_fuel_mass(100756), 50346);
+    }
+}