From 9607567aa9bba8e2e83f3f3a38c4eb0f0ecb2017 Mon Sep 17 00:00:00 2001 From: Justin Worthe Date: Thu, 22 Dec 2016 15:51:25 +0200 Subject: AOC21 --- aoc21/src/main.rs | 233 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 233 insertions(+) create mode 100644 aoc21/src/main.rs (limited to 'aoc21/src') diff --git a/aoc21/src/main.rs b/aoc21/src/main.rs new file mode 100644 index 0000000..1366f1e --- /dev/null +++ b/aoc21/src/main.rs @@ -0,0 +1,233 @@ +extern crate regex; + +use std::io::BufReader; +use std::io::prelude::*; +use std::fs::File; +use std::collections::VecDeque; + +use regex::Regex; + +fn main() { + let password = "abcdefgh".to_string(); + let program = read_file(); + let scrambled = scramble_password(password, &program); + println!("Scrambled password is {}", scrambled); + let unscrambled = unscramble_password(scrambled, &program); + println!("Which unscrambles to {}", unscrambled); + + let other_scrambled = "fbgdceah".to_string(); + let other_unscrambled = unscramble_password(other_scrambled, &program); + + println!("Decrypted easter bunny password is {}", other_unscrambled); +} + +fn read_file() -> Vec { + let file = BufReader::new(File::open("input.txt").unwrap()); + file.lines() + .map(|line| line.unwrap().trim().to_string()) + .filter(|line| line.len() > 0) + .collect() +} + +fn scramble_password(password: String, program: &Vec) -> String { + let mut pass = password.chars().collect::>(); + + let instructions = scramble_instruction_set(); + + for line in program { + for &(ref reg, ref func) in &instructions { + let captures = reg.captures(line.as_ref()); + if captures.is_some() { + func(&mut pass, captures.unwrap()); + } + } + } + + pass.iter().cloned().collect() +} + +fn unscramble_password(password: String, program: &Vec) -> String { + let mut pass = password.chars().collect::>(); + + let instructions = unscramble_instruction_set(); + + let mut backwards_program = program.clone(); + backwards_program.reverse(); + for line in backwards_program { + for &(ref reg, ref func) in &instructions { + let captures = reg.captures(line.as_ref()); + if captures.is_some() { + func(&mut pass, captures.unwrap()); + } + } + } + + pass.iter().cloned().collect() +} + +fn scramble_instruction_set() -> Vec<(Regex, fn(&mut VecDeque, regex::Captures))> { + let mut instructions : Vec<(Regex, fn(&mut VecDeque, regex::Captures))> = Vec::new(); + instructions.push((Regex::new(r"swap position (\d+) with position (\d+)").unwrap(), swap_pos)); + instructions.push((Regex::new(r"swap letter ([a-z]) with letter ([a-z])").unwrap(), swap_let)); + instructions.push((Regex::new(r"rotate left (\d+) step").unwrap(), rotate_left)); + instructions.push((Regex::new(r"rotate right (\d+) step").unwrap(), rotate_right)); + instructions.push((Regex::new(r"rotate based on position of letter ([a-z])").unwrap(), rotate_pos)); + instructions.push((Regex::new(r"reverse positions (\d+) through (\d+)").unwrap(), reverse_sub)); + instructions.push((Regex::new(r"move position (\d+) to position (\d+)").unwrap(), move_pos)); + + instructions +} + +fn unscramble_instruction_set() -> Vec<(Regex, fn(&mut VecDeque, regex::Captures))> { + let mut instructions : Vec<(Regex, fn(&mut VecDeque, regex::Captures))> = Vec::new(); + instructions.push((Regex::new(r"swap position (\d+) with position (\d+)").unwrap(), swap_pos)); + instructions.push((Regex::new(r"swap letter ([a-z]) with letter ([a-z])").unwrap(), swap_let)); + instructions.push((Regex::new(r"rotate left (\d+) step").unwrap(), rotate_right)); + instructions.push((Regex::new(r"rotate right (\d+) step").unwrap(), rotate_left)); + instructions.push((Regex::new(r"rotate based on position of letter ([a-z])").unwrap(), undo_rotate_pos)); + instructions.push((Regex::new(r"reverse positions (\d+) through (\d+)").unwrap(), reverse_sub)); + instructions.push((Regex::new(r"move position (\d+) to position (\d+)").unwrap(), undo_move_pos)); + + instructions +} + +fn swap_pos(pass: &mut VecDeque, cap: regex::Captures) { + let src = cap.at(1).unwrap().parse::().unwrap(); + let dest = cap.at(2).unwrap().parse::().unwrap(); + pass.swap(src, dest); +} + +fn swap_let(pass: &mut VecDeque, cap: regex::Captures) { + let src = cap.at(1).unwrap().chars().next().unwrap(); + let dest = cap.at(2).unwrap().chars().next().unwrap(); + let src_position = pass.iter().position(|&c| c == src); + let dest_position = pass.iter().position(|&c| c == dest); + match (src_position, dest_position) { + (Some(src_pos), Some(dest_pos)) => { + pass.swap(src_pos, dest_pos); + }, + _ => {} + }; +} + +fn rotate_left(pass: &mut VecDeque, cap: regex::Captures) { + let steps = cap.at(1).unwrap().parse::().unwrap(); + for _ in 0..steps { + let c = pass.pop_front().unwrap(); + pass.push_back(c); + } +} + +fn rotate_right(pass: &mut VecDeque, cap: regex::Captures) { + let steps = cap.at(1).unwrap().parse::().unwrap(); + for _ in 0..steps { + let c = pass.pop_back().unwrap(); + pass.push_front(c); + } +} + +fn rotate_pos(pass: &mut VecDeque, cap: regex::Captures) { + let letter = cap.at(1).unwrap().chars().next().unwrap(); + let pos = pass.iter().position(|&c| c == letter).unwrap(); + let steps = 1 + pos + if pos >=4 { 1 } else { 0 }; + for _ in 0..steps { + let c = pass.pop_back().unwrap(); + pass.push_front(c); + } +} + +fn move_pos(pass: &mut VecDeque, cap: regex::Captures) { + let src = cap.at(1).unwrap().parse::().unwrap(); + let dest = cap.at(2).unwrap().parse::().unwrap(); + let c = pass.remove(src).unwrap(); + pass.insert(dest, c); +} + +fn reverse_sub(pass: &mut VecDeque, cap: regex::Captures) { + let mut start = cap.at(1).unwrap().parse::().unwrap(); + let mut end = cap.at(2).unwrap().parse::().unwrap(); + while start < end { + pass.swap(start, end); + start += 1; + end -= 1; + } +} + +fn undo_rotate_pos(pass: &mut VecDeque, cap: regex::Captures) { + let letter = cap.at(1).unwrap().chars().next().unwrap(); + let dest_pos = pass.iter().position(|&c| c == letter).unwrap(); + let mut pos = dest_pos; + + loop { + let c = pass.pop_front().unwrap(); + pass.push_back(c); + pos -= 1; + let steps = 1 + pos + if pos >=4 { 1 } else { 0 }; + if (pos + steps) % pass.len() == dest_pos { + break; + } + } +} + +fn undo_move_pos(pass: &mut VecDeque, cap: regex::Captures) { + let src = cap.at(1).unwrap().parse::().unwrap(); + let dest = cap.at(2).unwrap().parse::().unwrap(); + let c = pass.remove(dest).unwrap(); + pass.insert(src, c); +} + +#[test] +fn swap_pos_example() { + let instructions = vec!("swap position 4 with position 0".to_string()); + let password = "abcde".to_string(); + assert_eq!("ebcda".to_string(), scramble_password(password, instructions)); +} + +#[test] +fn swap_let_example() { + let instructions = vec!("swap letter d with letter b".to_string()); + let password = "ebcda".to_string(); + assert_eq!("edcba".to_string(), scramble_password(password, instructions)); +} + +#[test] +fn reverse_example() { + let instructions = vec!("reverse positions 0 through 4".to_string()); + let password = "edcba".to_string(); + assert_eq!("abcde".to_string(), scramble_password(password, instructions)); +} + +#[test] +fn rotate_left_example() { + let instructions = vec!("rotate left 1 step".to_string()); + let password = "abcde".to_string(); + assert_eq!("bcdea".to_string(), scramble_password(password, instructions)); +} + +#[test] +fn move_example() { + let instructions = vec!("move position 3 to position 0".to_string()); + let password = "bdeac".to_string(); + assert_eq!("abdec".to_string(), scramble_password(password, instructions)); +} + +#[test] +fn rotate_pos_example_1() { + let instructions = vec!("rotate based on position of letter b".to_string()); + let password = "abdec".to_string(); + assert_eq!("ecabd".to_string(), scramble_password(password, instructions)); +} + +#[test] +fn rotate_pos_example_2() { + let instructions = vec!("rotate based on position of letter d".to_string()); + let password = "ecabd".to_string(); + assert_eq!("decab".to_string(), scramble_password(password, instructions)); +} + +#[test] +fn rotate_right_example() { + let instructions = vec!("rotate right 2 steps".to_string()); + let password = "decab".to_string(); + assert_eq!("abdec".to_string(), scramble_password(password, instructions)); +} -- cgit v1.2.3