AOC-2019-03.rs

use std::collections::HashMap;

fn to_wire(wire: &str) -> HashMap<(i32, i32), i32> {
    let mut c: (i32, i32) = (0, 0);
    let mut v = HashMap::new();
    let mut s = 1;
    for dir in wire.split(",") {
        let n: i32 = dir[1..].parse().unwrap();
        for _ in 0..n {
            if dir.starts_with("L") {
                c.0 -= 1;
            } else if dir.starts_with("R") {
                c.0 += 1;
            } else if dir.starts_with("U") {
                c.1 -= 1;
            } else if dir.starts_with("D") {
                c.1 += 1;
            }
            v.entry(c).or_insert(s);
            s += 1;
        }
    }
    v
}

fn find_intersection(w1: HashMap<(i32, i32), i32>, w2: HashMap<(i32, i32), i32>) -> (i32, i32) {
    let mut m1: i32 = std::i32::MAX;
    let mut m2: i32 = std::i32::MAX;
    for (p, s1) in &w1 {
        let m = w2.get(p);
        if let Some(s2) = m {
            let d1 = p.0.abs() + p.1.abs();
            if d1 < m1 {
                m1 = d1;
            }
            let d2 = s1 + s2;
            if d2 < m2 {
                m2 = d2;
            }
        }
    }
    (m1, m2)
}

fn run(input: &str) -> (i32, i32) {
    let wires: Vec<&str> = input.split("\n").collect();
    let wire1 = to_wire(wires[0]);
    let wire2 = to_wire(wires[1]);
    find_intersection(wire1, wire2)
}

fn main() {
    let input = include_str!("../input/2019-03");
    let (p1, p2) = run(input);
    println!("p1: {}", p1);
    println!("p1: {}", p2);
}

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

    #[test]
    fn test1() {
        let (p1, p2) = run("R75,D30,R83,U83,L12,D49,R71,U7,L72\nU62,R66,U55,R34,D71,R55,D58,R83");
        assert_eq!(p1, 159);
        assert_eq!(p2, 610);
    }

    #[test]
    fn test2() {
        let (p1, p2) = run("R98,U47,R26,D63,R33,U87,L62,D20,R33,U53,R51\nU98,R91,D20,R16,D67,R40,U7,R15,U6,R7");
        assert_eq!(p1, 135);
        assert_eq!(p2, 410);
    }
}