Solution for Advent of Code 2017 Day 5

day05.rs

use std::time::Instant;

const INPUT: &str = include_str!("inputs/day05.txt");

fn parse(input: &str) -> Vec<isize> {
    input.lines().map(|l| l.parse::<isize>().unwrap()).collect()
}

fn p1(input: &str) -> usize {
    let mut input = parse(input);
    let mut pc = 0isize;
    let mut steps = 0usize;
    while pc >= 0 && pc < input.len() as isize {
        steps += 1;
        let cur_pc = pc;
        pc += input[pc as usize];
        input[cur_pc as usize] += 1;
    }
    steps
}

fn p2(input: &str) -> usize {
    let mut input = parse(input);
    let mut pc = 0isize;
    let mut steps = 0usize;
    while pc >= 0 && pc < input.len() as isize {
        steps += 1;
        let cur_pc = pc;
        pc += input[pc as usize];
        if input[cur_pc as usize] >= 3 {
            input[cur_pc as usize] -= 1;
        } else {
            input[cur_pc as usize] += 1;
        }
    }
    steps
}

fn main() {
    let now = Instant::now();
    let solution = p1(INPUT);
    println!("p1 {:?} {}", now.elapsed(), solution);

    let now = Instant::now();
    let solution = p2(INPUT);
    println!("p2 {:?} {}", now.elapsed(), solution);
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_p1() {
        let input = "0\n3\n0\n1\n-3";
        assert_eq!(p1(input), 5);
    }

    #[test]
    fn test_p2() {
        let input = "0\n3\n0\n1\n-3";
        assert_eq!(p2(input), 10);
    }
}