1 files changed, 136 insertions, 0 deletions
diff --git a/2016/aoc12/src/main.rs b/2016/aoc12/src/main.rs
new file mode 100644
index 0000000..2356402
--- /dev/null
+++ b/2016/aoc12/src/main.rs
@@ -0,0 +1,136 @@
+extern crate regex;
+use regex::Regex;
+
+use std::io::BufReader;
+use std::io::prelude::*;
+use std::fs::File;
+
+enum Instruction {
+    CpyLit(i32, usize),
+    CpyReg(usize, usize),
+    Inc(usize),
+    Dec(usize),  
+    Jnz(usize, i32),
+    Jmp(i32),
+    Noop
+}
+
+impl Instruction {
+    fn parse(line: &str) -> Instruction {
+        let cpy_lit: Regex = Regex::new(r"cpy ([-\d]+) (a|b|c|d)").unwrap();
+        let cpy_reg = Regex::new(r"cpy (a|b|c|d) (a|b|c|d)").unwrap();
+        let inc = Regex::new(r"inc (a|b|c|d)").unwrap();
+        let dec = Regex::new(r"dec (a|b|c|d)").unwrap();
+        let jnz_lit = Regex::new(r"jnz ([-\d]+) ([-\d]+)").unwrap();
+        let jnz_reg = Regex::new(r"jnz (a|b|c|d) ([-\d]+)").unwrap();
+
+        let cpy_lit_match = cpy_lit.captures(line);
+        let cpy_reg_match = cpy_reg.captures(line);
+        let inc_match = inc.captures(line);
+        let dec_match = dec.captures(line);
+        let jnz_lit_match = jnz_lit.captures(line);
+        let jnz_reg_match = jnz_reg.captures(line);
+        
+        if cpy_lit_match.is_some() {
+            let cap = cpy_lit_match.unwrap();
+            let src: i32 = cap.at(1).unwrap().parse().unwrap();
+            let dest = to_register_index(cap.at(2).unwrap());
+            Instruction::CpyLit(src, dest)
+        }
+        else if cpy_reg_match.is_some() {
+            let cap = cpy_reg_match.unwrap();
+            let src = to_register_index(cap.at(1).unwrap());
+            let dest = to_register_index(cap.at(2).unwrap());
+            Instruction::CpyReg(src, dest)
+        }
+        else if inc_match.is_some() {
+            let cap = inc_match.unwrap();
+            let dest = to_register_index(cap.at(1).unwrap());
+            Instruction::Inc(dest)
+        }
+        else if dec_match.is_some() {
+            let cap = dec_match.unwrap();
+            let dest = to_register_index(cap.at(1).unwrap());
+            Instruction::Dec(dest)
+        }
+        else if jnz_lit_match.is_some() {
+            let cap = jnz_lit_match.unwrap();
+            let condition: i32 = cap.at(1).unwrap().parse().unwrap();
+            let offset: i32 = cap.at(2).unwrap().parse().unwrap();
+            if condition != 0 {
+                Instruction::Jmp(offset)
+            }
+            else {
+                Instruction::Noop
+            }
+        }
+        else if jnz_reg_match.is_some() {
+            let cap = jnz_reg_match.unwrap();
+            let condition = to_register_index(cap.at(1).unwrap());
+            let offset: i32 = cap.at(2).unwrap().parse().unwrap();
+            Instruction::Jnz(condition, offset)
+        }
+        else {
+            panic!("Invalid instruction line")
+        }
+    }
+}
+
+fn main() {
+    let program = read_file();
+
+    let mut registers: [i32; 4] = [0, 0, 1, 0];
+    let mut pc: usize = 0;
+    
+    while pc < program.len() {
+        let mut pc_next: usize = pc+1;
+
+        match program[pc] {
+            Instruction::CpyLit(src, dest) => {
+                registers[dest] = src;
+            },
+            Instruction::CpyReg(src, dest) => {
+                registers[dest] = registers[src];
+            },
+            Instruction::Inc(dest) => {
+                registers[dest] += 1;
+            },
+            Instruction::Dec(dest) => {
+                registers[dest] -= 1;
+            },
+            Instruction::Jnz(condition, offset) => {
+                if registers[condition] != 0 {
+                    pc_next = (pc as i32 + offset) as usize;
+                }
+            },
+            Instruction::Jmp(offset) => {
+                pc_next = (pc as i32 + offset) as usize
+            },
+            Instruction::Noop => {}
+        }
+
+        pc = pc_next;
+    }
+    
+    println!("a: {}, b: {}, c: {}, d: {}", registers[0], registers[1], registers[2], registers[3]);
+    
+}
+
+fn to_register_index(name: &str) -> usize {
+    match name {
+        "a" => 0,
+        "b" => 1,
+        "c" => 2,
+        "d" => 3,
+        _ => panic!("Invalid register provided")
+    }
+}
+
+fn read_file() -> Vec<Instruction> {
+    let file = BufReader::new(File::open("input.txt").unwrap());
+    file.lines()
+        .map(|line| line.unwrap())
+        .filter(|line| line.len() > 0)
+        .map(|line| Instruction::parse(line.trim()))
+        .collect()
+}