A sample implementation of Advent of Code 2019 Day 2 in Rust

AoC2019D2V1.rs

fn solve(input: &str) -> impl Display {
    let init: Vec<Cell<usize>> = input
        .trim()
        .split(',')
        .map(|value| value.parse::<usize>().unwrap().into())
        .collect();


    let mut memory = Vec::new();


    for noun in 0..100 {
        for verb in 0..100 {
            memory.clone_from(&init);


            memory[1].set(noun);
            memory[2].set(verb);


            for op in memory.chunks(4) {
                match op[0].get() {
                    99 => break,
                    code => {
                        let lhs = memory[op[1].get()].get();
                        let rhs = memory[op[2].get()].get();


                        let output = match code {
                            1 => lhs + rhs,
                            2 => lhs * rhs,
                            _ => panic!("Invalid opcode: {}", code),
                        };


                        memory[op[3].get()].set(output);
                    }
                }
            }


            if memory[0].get() == 19690720 {
                return (100 * noun) + verb;
            }
        }
    }
    panic!("Couldn't find a solution")
}