2016: 01

2016/.gitignore

@@ -0,0 +1,14 @@
+# Generated by Cargo
+# will have compiled files and executables
+debug/
+target/
+
+# Remove Cargo.lock from gitignore if creating an executable, leave it for libraries
+# More information here https://doc.rust-lang.org/cargo/guide/cargo-toml-vs-cargo-lock.html
+Cargo.lock
+
+# These are backup files generated by rustfmt
+**/*.rs.bk
+
+# MSVC Windows builds of rustc generate these, which store debugging information
+*.pdb

2016/aoc01/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "aoc01"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

2016/aoc01/input

@@ -0,0 +1 @@
+R4, R4, L1, R3, L5, R2, R5, R1, L4, R3, L5, R2, L3, L4, L3, R1, R5, R1, L3, L1, R3, L1, R2, R2, L2, R5, L3, L4, R4, R4, R2, L4, L1, R5, L1, L4, R4, L1, R1, L2, R5, L2, L3, R2, R1, L194, R2, L4, R49, R1, R3, L5, L4, L1, R4, R2, R1, L5, R3, L5, L4, R4, R4, L2, L3, R78, L5, R4, R191, R4, R3, R1, L2, R1, R3, L1, R3, R4, R2, L2, R1, R4, L5, R2, L2, L4, L2, R1, R2, L3, R5, R2, L3, L3, R3, L1, L1, R5, L4, L4, L2, R5, R1, R4, L3, L5, L4, R5, L4, R5, R4, L3, L2, L5, R4, R3, L3, R1, L5, R5, R1, L3, R2, L5, R5, L3, R1, R4, L5, R4, R2, R3, L4, L5, R3, R4, L5, L5, R4, L4, L4, R1, R5, R3, L1, L4, L3, L4, R1, L5, L1, R2, R2, R4, R4, L5, R4, R1, L1, L1, L3, L5, L2, R4, L3, L5, L4, L1, R3

2016/aoc01/src/main.rs

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+use std::collections::HashMap;
+use std::{fs, io, process};
+use std::io::BufRead;
+
+enum Direction {
+    Right,
+    Left
+}
+
+struct Instruction {
+    direction: Direction,
+    steps: i32,
+}
+
+fn read_instructions(filename: &str) -> Vec<Instruction> {
+    let mut vec: Vec<Instruction> = Vec::new();
+
+    let file = fs::File::open(filename).expect("File not found");
+
+    let lines = io::BufReader::new(file).lines();
+    for line_res in lines {
+        if let Ok(line) = line_res {
+            let instructions = line.split(", ");
+            for instruction in instructions {
+                let direction = match instruction.chars().nth(0) {
+                    Some('L') => Direction::Left,
+                    Some('R') => Direction::Right,
+                    _ => process::exit(1), // not elegant
+                };
+                vec.push(Instruction{direction: direction, steps: instruction.to_string()[1..].parse::<i32>().unwrap()});
+            }
+        }
+    }
+    return vec;
+}
+
+fn part1(instructions: &Vec<Instruction>) -> i32 {
+    let mut position = (0,0);
+    let mut direction = (1,0);
+    for instruction in instructions {
+        direction = match instruction.direction {
+            Direction::Right => (-direction.1, direction.0),
+            Direction::Left => (direction.1, -direction.0),
+        };
+        position = (position.0 + instruction.steps * direction.0, position.1 + instruction.steps * direction.1);
+    }
+
+    return position.0.abs() + position.1.abs();
+}
+
+fn part2(instructions: &Vec<Instruction>) -> i32 {
+    let mut position = (0,0);
+    let mut direction = (1,0);
+    let mut map: HashMap<(i32, i32), i32> = HashMap::new();
+    map.insert((0,0), 1);
+    for instruction in instructions {
+        direction = match instruction.direction {
+            Direction::Right => (-direction.1, direction.0),
+            Direction::Left => (direction.1, -direction.0),
+        };
+        for _ in 0..instruction.steps {
+            position = (position.0 + direction.0, position.1 + direction.1);
+            if map.contains_key(&position) {
+                return position.0.abs() + position.1.abs();
+            } else {
+                map.insert(position, 1);
+            }
+        }
+    }
+
+    return -1;
+}
+
+fn main() {
+    let instructions = read_instructions("input");
+    println!("The Easter Bunny HQ is {} blocks away", part1(&instructions));
+    println!("The Easter Bunny HQ is actually {} blocks away", part2(&instructions));
+}