98 lines
3.1 KiB
Rust
98 lines
3.1 KiB
Rust
#![warn(clippy::all, clippy::pedantic)]
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mod common;
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use common::day_input;
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#[derive(Debug)]
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struct Vec2 { x: i64, y: i64 }
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#[derive(Debug)]
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struct Rect { top_left: Vec2, bottom_right: Vec2 }
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fn parse_target_rect(s: &str) -> Rect {
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let mut nums: Vec<Vec<i64>> =
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s
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.split(": ")
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.nth(1).unwrap()
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.split(", ")
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.take(2)
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.map(|s| s.split("=")
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.nth(1).unwrap()
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.split("..")
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.map(|s2| {
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// println!("Parsing Int: {}", s2);
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s2.parse::<i64>().unwrap()
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})
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.take(2)
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.collect()
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).collect();
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let mut xr: Vec<i64> = nums.remove(0);
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let mut yr: Vec<i64> = nums.remove(0);
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xr.sort();
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yr.sort();
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Rect { top_left: Vec2 { x: xr[0], y: yr[1] }, bottom_right: Vec2 { x: xr[1], y: yr[0] } }
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}
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fn simulate_shot(initial_vel: Vec2, target: &Rect) -> Result<(Vec2, i64), (Vec2, Vec2)> {
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let mut vel = Vec2 { x: initial_vel.x, y: initial_vel.y };
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let mut last_pos = Vec2 { x: 0, y: 0 };
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let mut x: i64 = 0;
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let mut y: i64 = 0;
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let mut highest_y = y;
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while x <= target.bottom_right.x && y >= target.bottom_right.y {
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// println!("At {}, {} (lim: {}->{}, {}->{})", x, y, target.top_left.x, target.bottom_right.x, target.top_left.y, target.bottom_right.y);
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if x >= target.top_left.x && y <= target.top_left.y && x <= target.bottom_right.x && y >= target.bottom_right.y {
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// println!("Ding!: {}, {} (lim: {}->{}, {}->{})", x, y, target.top_left.x, target.bottom_right.x, target.top_left.y, target.bottom_right.y);
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return Ok((Vec2 { x, y }, highest_y));
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}
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last_pos = Vec2 { x, y };
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x += vel.x;
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y += vel.y;
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if vel.x != 0 {
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if vel.x > 0 { vel.x -= 1; }
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else { vel.x += 1; }
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}
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if y > highest_y { highest_y = y; }
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vel.y -= 1
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}
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// println!("Too Far: {}, {} (lim: {}->{}, {}->{})", x, y, target.top_left.x, target.bottom_right.x, target.top_left.y, target.bottom_right.y);
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Err((Vec2 { x, y }, last_pos))
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}
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fn trick_shot(r: &Rect) -> (Option<i64>, i64) {
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let mut result = None;
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let mut valid_shots = 0;
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for x in 1..=r.bottom_right.x {
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for y in r.bottom_right.y..=-r.bottom_right.y*2 {
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// println!("Simulating {}, {}", x, y);
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if let Ok((v, hy)) = simulate_shot(Vec2 { x, y }, r) {
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valid_shots += 1;
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if result.is_some() {
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if hy > result.unwrap() {
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// println!("!! New Highest Y: {} via {}, {}", hy, x, y);
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result = Some(hy);
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}
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} else {
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result = Some(hy);
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}
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}
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}
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}
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(result, valid_shots)
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}
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fn main() {
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let r = parse_target_rect(&day_input(17).trim());
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println!("Trick Shot Data: {:#?}", trick_shot(&r));
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn packet_op_result_examples() {
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let tester = |s: &str| trick_shot(&parse_target_rect(s));
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assert_eq!(tester("target area: x=20..30, y=-10..-5"), (Some(45), 112));
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}
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}
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