Implement day 19.

With nice hotspot optimization for part 2.

2018/inputs/19.txt

@@ -0,0 +1,37 @@
+#ip 3
+addi 3 16 3
+seti 1 8 1
+seti 1 3 4
+mulr 1 4 2
+eqrr 2 5 2
+addr 2 3 3
+addi 3 1 3
+addr 1 0 0
+addi 4 1 4
+gtrr 4 5 2
+addr 3 2 3
+seti 2 6 3
+addi 1 1 1
+gtrr 1 5 2
+addr 2 3 3
+seti 1 5 3
+mulr 3 3 3
+addi 5 2 5
+mulr 5 5 5
+mulr 3 5 5
+muli 5 11 5
+addi 2 5 2
+mulr 2 3 2
+addi 2 21 2
+addr 5 2 5
+addr 3 0 3
+seti 0 4 3
+setr 3 1 2
+mulr 2 3 2
+addr 3 2 2
+mulr 3 2 2
+muli 2 14 2
+mulr 2 3 2
+addr 5 2 5
+seti 0 3 0
+seti 0 6 3

2018/src/day19.rs

@@ -1,25 +1,218 @@
 use std::io::Read;
 
 use common::Solution;
+use std::io::BufReader;
+use std::io::BufRead;
+
+#[derive(Copy, Clone, Debug, Hash, Eq, PartialEq)]
+enum OpCode {
+    ADDR,
+    ADDI,
+    MULR,
+    MULI,
+    BANR,
+    BANI,
+    BORR,
+    BORI,
+    SETR,
+    SETI,
+    GTIR,
+    GTRI,
+    GTRR,
+    EQIR,
+    EQRI,
+    EQRR,
+}
+
+impl OpCode {
+    fn valid(self, op: &[i32; 4], before: &[i32; 4], after: &[i32; 4]) -> bool {
+        let mut cpu = CPU::new();
+
+        cpu.registers.copy_from_slice(before);
+        if let Ok(val) = cpu.execute(self, &op[1..4]) {
+            if val == after[op[3] as usize] {
+                return true;
+            }
+        }
+
+        false
+    }
+}
+
+impl From<&str> for OpCode {
+    fn from(name: &str) -> Self {
+        match name {
+            "addr" => OpCode::ADDR,
+            "addi" => OpCode::ADDI,
+            "mulr" => OpCode::MULR,
+            "muli" => OpCode::MULI,
+            "banr" => OpCode::BANR,
+            "bani" => OpCode::BANI,
+            "borr" => OpCode::BORR,
+            "bori" => OpCode::BORI,
+            "setr" => OpCode::SETR,
+            "seti" => OpCode::SETI,
+            "gtir" => OpCode::GTIR,
+            "gtri" => OpCode::GTRI,
+            "gtrr" => OpCode::GTRR,
+            "eqir" => OpCode::EQIR,
+            "eqri" => OpCode::EQRI,
+            "eqrr" => OpCode::EQRR,
+            _ => panic!("Invalid opcode {}", name),
+        }
+    }
+}
+
+const OP_LIST: [OpCode; 16] = [
+    OpCode::ADDR,
+    OpCode::ADDI,
+    OpCode::MULR,
+    OpCode::MULI,
+    OpCode::BANR,
+    OpCode::BANI,
+    OpCode::BORR,
+    OpCode::BORI,
+    OpCode::SETR,
+    OpCode::SETI,
+    OpCode::GTIR,
+    OpCode::GTRI,
+    OpCode::GTRR,
+    OpCode::EQIR,
+    OpCode::EQRI,
+    OpCode::EQRR,
+];
+
+#[derive(Debug)]
+enum CPUErr {
+    InvalidRegister(i32),
+}
 
 #[derive(Default)]
-pub struct Day19 {}
+struct CPU {
+    registers: [i32; 6],
+}
+
+impl CPU {
+    pub fn new() -> Self {
+        Default::default()
+    }
+    pub fn execute(&mut self, op: OpCode, var: &[i32]) -> Result<i32, CPUErr> {
+        use self::OpCode::*;
+        let res = match op {
+            ADDR => self.reg(var[0])? + self.reg(var[1])?,
+            ADDI => self.reg(var[0])? + var[1],
+            MULR => self.reg(var[0])? * self.reg(var[1])?,
+            MULI => self.reg(var[0])? * var[1],
+            BANR => self.reg(var[0])? & self.reg(var[1])?,
+            BANI => self.reg(var[0])? & var[1],
+            BORR => self.reg(var[0])? | self.reg(var[1])?,
+            BORI => self.reg(var[0])? | var[1],
+            SETR => self.reg(var[0])?,
+            SETI => var[0],
+            GTRR => (self.reg(var[0])? > self.reg(var[1])?).into(),
+            GTIR => (var[0] > self.reg(var[1])?).into(),
+            GTRI => (self.reg(var[0])? > var[1]).into(),
+            EQRR => (self.reg(var[0])? == self.reg(var[1])?).into(),
+            EQIR => (var[0] == self.reg(var[1])?).into(),
+            EQRI => (self.reg(var[0])? == var[1]).into(),
+        };
+
+        self.registers[var[2] as usize] = res;
+        Ok(res)
+    }
+
+    fn reg(&self, index: i32) -> Result<i32, CPUErr> {
+        if let Some(val) = self.registers.get(index as usize) {
+            Ok(*val)
+        } else {
+            Err(CPUErr::InvalidRegister(index))
+        }
+    }
+}
+
+#[derive(Default)]
+pub struct Day19 {
+    program: Vec<(OpCode, [i32; 3])>,
+    ip: usize,
+}
 
 impl Day19 {
     pub fn new() -> Self {
         Default::default()
     }
+
+    fn read_input(&mut self, input: &mut Read) {
+        let reader = BufReader::new(input);
+
+        for line in reader.lines() {
+            let line = line.unwrap();
+            if line.chars().next().unwrap() == '#' {
+                self.ip = line.split(' ').last().unwrap().parse().unwrap();
+            } else {
+                let mut parts = line.split(' ');
+                let opcode = OpCode::from(parts.next().unwrap());
+                let mut operands = [0; 3];
+                for i in 0..3 {
+                    operands[i] = parts.next().unwrap().parse().unwrap();
+                }
+
+                self.program.push((opcode, operands));
+            }
+        }
+    }
 }
 
 impl Solution for Day19 {
-    fn part1(&mut self, _input: &mut Read) -> String {
-        unimplemented!()
+    fn part1(&mut self, input: &mut Read) -> String {
+        self.read_input(input);
+
+        let mut cpu = CPU::new();
+
+        while (cpu.registers[self.ip] as usize) < self.program.len() {
+            let (opcode, operands) = &self.program[cpu.registers[self.ip] as usize];
+            cpu.execute(*opcode, operands);
+            cpu.registers[self.ip] += 1;
+        }
+
+        format!("{}", cpu.registers[0])
     }
 
-    fn part2(&mut self, _input: &mut Read) -> String {
-        unimplemented!()
+    fn part2(&mut self, input: &mut Read) -> String {
+        self.read_input(input);
+
+        let mut cpu = CPU::new();
+        cpu.registers[0] = 1;
+
+        // This is optimized for my input.
+        assert_eq!(self.ip, 3);
+
+        while (cpu.registers[3] as usize) < self.program.len() {
+            if cpu.registers[3] == 3 {
+                let reg = &mut cpu.registers;
+                if reg[5] % reg[1] == 0 {
+                    reg[0] += reg[1];
+                }
+                reg[3] = 12;
+            }
+            let (opcode, operands) = &self.program[cpu.registers[self.ip] as usize];
+            cpu.execute(*opcode, operands);
+            cpu.registers[self.ip] += 1;
+        }
+
+        format!("{}", cpu.registers[0])
     }
 }
 
 #[cfg(test)]
-mod tests {}
+mod tests {
+    use day19::Day19;
+    use common::Solution;
+
+    const SAMPLE_INPUT: &[u8] = include_bytes!("samples/19.txt");
+
+    #[test]
+    fn sample_part1() {
+        let mut instance = Day19::new();
+        assert_eq!("6", instance.part1(&mut SAMPLE_INPUT));
+    }
+}

2018/src/samples/19.txt

@@ -0,0 +1,8 @@
+#ip 0
+seti 5 0 1
+seti 6 0 2
+addi 0 1 0
+addr 1 2 3
+setr 1 0 0
+seti 8 0 4
+seti 9 0 5