Add day17 part1

day17/Cargo.lock

@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "day17"
+version = "0.1.0"

day17/Cargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "day17"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]

day17/src/main.rs

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+#[derive(Debug)]
+struct State {
+    reg_a: usize,
+    reg_b: usize,
+    reg_c: usize,
+    prog: Vec<u8>,
+    pc: usize,
+    out: Vec<String>,
+}
+
+impl State {
+    fn get_combo_operand(&self) -> usize {
+        match self.prog[self.pc + 1] {
+            x @ 0..=3 => x as usize,
+            4 => self.reg_a,
+            5 => self.reg_b,
+            6 => self.reg_c,
+            _ => panic!(),
+        }
+    }
+    fn exec_instruction(&mut self) {
+        let literal_op = self.prog[self.pc + 1];
+        match self.prog[self.pc] {
+            0 => self.reg_a /= 2 << (self.get_combo_operand() - 1),
+            1 => self.reg_b ^= literal_op as usize,
+            2 => self.reg_b = self.get_combo_operand() % 8,
+            3 => {
+                if self.reg_a != 0 {
+                    self.pc = literal_op as usize;
+                    return;
+                }
+            }
+            4 => self.reg_b ^= self.reg_c,
+            5 => self.out.push((self.get_combo_operand() % 8).to_string()),
+            6 => self.reg_b = self.reg_a / (2 << (self.get_combo_operand() - 1)),
+            7 => self.reg_c = self.reg_a / (2 << (self.get_combo_operand() - 1)),
+            _ => panic!("Invalid instruction"),
+        }
+        self.pc += 2;
+    }
+}
+
+fn parse(input: &str) -> State {
+    let (registers, program) = input.split_once("\n\n").unwrap();
+    let &[a, b, c] = registers
+        .lines()
+        .map(|l| l.split(' ').last().unwrap().parse().unwrap())
+        .collect::<Vec<_>>()
+        .as_slice()
+    else {
+        panic!()
+    };
+    State {
+        reg_a: a,
+        reg_b: b,
+        reg_c: c,
+        prog: program
+            .split_once(' ')
+            .unwrap()
+            .1
+            .trim()
+            .split(',')
+            .map(|i| i.parse().unwrap())
+            .collect(),
+        pc: 0,
+        out: vec![],
+    }
+}
+
+fn part1(state: &mut State) -> String {
+    while state.pc < state.prog.len() - 1 {
+        state.exec_instruction();
+    }
+    state.out.join(",")
+}
+
+fn main() {
+    let mut input = parse(include_str!("../input.txt"));
+    println!("{}", part1(&mut input));
+}