Refile for merging repos

4 files changed, 438 insertions, 0 deletions

diff --git a/2016/aoc21/Cargo.lock b/2016/aoc21/Cargo.lock
new file mode 100644
index 0000000..9a1075b
--- /dev/null
+++ b/2016/aoc21/Cargo.lock
@@ -0,0 +1,98 @@
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diff --git a/2016/aoc21/Cargo.toml b/2016/aoc21/Cargo.toml
new file mode 100644
index 0000000..bc0d468
--- /dev/null
+++ b/2016/aoc21/Cargo.toml
@@ -0,0 +1,7 @@
+[package]
+name = "aoc21"
+version = "0.1.0"
+authors = ["Justin Worthe <justin.worthe@gmail.com>"]
+
+[dependencies]
+regex = "0.1"
\ No newline at end of file
diff --git a/2016/aoc21/input.txt b/2016/aoc21/input.txt
new file mode 100644
index 0000000..ebd7d52
--- /dev/null
+++ b/2016/aoc21/input.txt
@@ -0,0 +1,100 @@
+rotate based on position of letter d
+move position 1 to position 6
+swap position 3 with position 6
+rotate based on position of letter c
+swap position 0 with position 1
+rotate right 5 steps
+rotate left 3 steps
+rotate based on position of letter b
+swap position 0 with position 2
+rotate based on position of letter g
+rotate left 0 steps
+reverse positions 0 through 3
+rotate based on position of letter a
+rotate based on position of letter h
+rotate based on position of letter a
+rotate based on position of letter g
+rotate left 5 steps
+move position 3 to position 7
+rotate right 5 steps
+rotate based on position of letter f
+rotate right 7 steps
+rotate based on position of letter a
+rotate right 6 steps
+rotate based on position of letter a
+swap letter c with letter f
+reverse positions 2 through 6
+rotate left 1 step
+reverse positions 3 through 5
+rotate based on position of letter f
+swap position 6 with position 5
+swap letter h with letter e
+move position 1 to position 3
+swap letter c with letter h
+reverse positions 4 through 7
+swap letter f with letter h
+rotate based on position of letter f
+rotate based on position of letter g
+reverse positions 3 through 4
+rotate left 7 steps
+swap letter h with letter a
+rotate based on position of letter e
+rotate based on position of letter f
+rotate based on position of letter g
+move position 5 to position 0
+rotate based on position of letter c
+reverse positions 3 through 6
+rotate right 4 steps
+move position 1 to position 2
+reverse positions 3 through 6
+swap letter g with letter a
+rotate based on position of letter d
+rotate based on position of letter a
+swap position 0 with position 7
+rotate left 7 steps
+rotate right 2 steps
+rotate right 6 steps
+rotate based on position of letter b
+rotate right 2 steps
+swap position 7 with position 4
+rotate left 4 steps
+rotate left 3 steps
+swap position 2 with position 7
+move position 5 to position 4
+rotate right 3 steps
+rotate based on position of letter g
+move position 1 to position 2
+swap position 7 with position 0
+move position 4 to position 6
+move position 3 to position 0
+rotate based on position of letter f
+swap letter g with letter d
+swap position 1 with position 5
+reverse positions 0 through 2
+swap position 7 with position 3
+rotate based on position of letter g
+swap letter c with letter a
+rotate based on position of letter g
+reverse positions 3 through 5
+move position 6 to position 3
+swap letter b with letter e
+reverse positions 5 through 6
+move position 6 to position 7
+swap letter a with letter e
+swap position 6 with position 2
+move position 4 to position 5
+rotate left 5 steps
+swap letter a with letter d
+swap letter e with letter g
+swap position 3 with position 7
+reverse positions 0 through 5
+swap position 5 with position 7
+swap position 1 with position 7
+swap position 1 with position 7
+rotate right 7 steps
+swap letter f with letter a
+reverse positions 0 through 7
+rotate based on position of letter d
+reverse positions 2 through 4
+swap position 7 with position 1
+swap letter a with letter h
diff --git a/2016/aoc21/src/main.rs b/2016/aoc21/src/main.rs
new file mode 100644
index 0000000..1366f1e
--- /dev/null
+++ b/2016/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<String> {
+    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>) -> String {
+    let mut pass = password.chars().collect::<VecDeque<_>>();    
+
+    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>) -> String {
+    let mut pass = password.chars().collect::<VecDeque<_>>();
+
+    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<char>, regex::Captures))> {
+    let mut instructions : Vec<(Regex, fn(&mut VecDeque<char>, 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<char>, regex::Captures))> {
+    let mut instructions : Vec<(Regex, fn(&mut VecDeque<char>, 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<char>, cap: regex::Captures) {
+    let src = cap.at(1).unwrap().parse::<usize>().unwrap();
+    let dest = cap.at(2).unwrap().parse::<usize>().unwrap();
+    pass.swap(src, dest);
+}
+
+fn swap_let(pass: &mut VecDeque<char>, 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<char>, cap: regex::Captures) {
+    let steps = cap.at(1).unwrap().parse::<usize>().unwrap();
+    for _ in 0..steps {
+        let c = pass.pop_front().unwrap();
+        pass.push_back(c);
+    }
+}
+
+fn rotate_right(pass: &mut VecDeque<char>, cap: regex::Captures) {
+    let steps = cap.at(1).unwrap().parse::<usize>().unwrap();
+    for _ in 0..steps {
+        let c = pass.pop_back().unwrap();
+        pass.push_front(c);
+    }
+}
+
+fn rotate_pos(pass: &mut VecDeque<char>, 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<char>, cap: regex::Captures) {
+    let src = cap.at(1).unwrap().parse::<usize>().unwrap();
+    let dest = cap.at(2).unwrap().parse::<usize>().unwrap();
+    let c = pass.remove(src).unwrap();
+    pass.insert(dest, c);
+}
+
+fn reverse_sub(pass: &mut VecDeque<char>, cap: regex::Captures) {
+    let mut start = cap.at(1).unwrap().parse::<usize>().unwrap();
+    let mut end = cap.at(2).unwrap().parse::<usize>().unwrap();
+    while start < end {
+        pass.swap(start, end);
+        start += 1;
+        end -= 1;
+    }
+}
+
+fn undo_rotate_pos(pass: &mut VecDeque<char>, 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<char>, cap: regex::Captures) {
+    let src = cap.at(1).unwrap().parse::<usize>().unwrap();
+    let dest = cap.at(2).unwrap().parse::<usize>().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));
+}