From 260f0cd6c39130aad263b1e7d14c54f326b5c0d5 Mon Sep 17 00:00:00 2001
From: Shadowfacts <me@shadowfacts.net>
Date: Fri, 17 Dec 2021 22:34:59 -0500
Subject: [PATCH] Day 17

---
 src/day17.rs | 40 ++++++++++++++++++++++++++++++++++++++++
 src/main.rs  |  3 ++-
 2 files changed, 42 insertions(+), 1 deletion(-)
 create mode 100644 src/day17.rs

diff --git a/src/day17.rs b/src/day17.rs
new file mode 100644
index 0000000..90a314f
--- /dev/null
+++ b/src/day17.rs
@@ -0,0 +1,40 @@
+use std::cmp::max;
+use std::ops::RangeInclusive;
+
+pub fn day17() {
+    solve(&(20..=30), &(-10..=-5));
+    solve(&(287..=309), &(-76..=-48));
+}
+
+fn solve(target_x: &RangeInclusive<isize>, target_y: &RangeInclusive<isize>) {
+    let maxes = (0..=*target_x.end()).flat_map(|vx| {
+        (*target_y.start()..=100).filter_map(move |vy| count_steps(vx, vy, target_x, target_y))
+    });
+    dbg!(maxes.clone().max());
+    dbg!(maxes.count());
+}
+
+fn count_steps(
+    mut vx: isize,
+    mut vy: isize,
+    target_x: &RangeInclusive<isize>,
+    target_y: &RangeInclusive<isize>,
+) -> Option<isize> {
+    let mut x = 0;
+    let mut y = 0;
+    let mut max_y = 0;
+    loop {
+        x += vx;
+        y += vy;
+        vx -= vx.signum();
+        vy -= 1;
+        max_y = max(max_y, y);
+        if target_x.contains(&x) && target_y.contains(&y) {
+            return Some(max_y);
+        } else if !target_x.contains(&x) && vx == 0 {
+            return None;
+        } else if !target_y.contains(&y) && y < *target_y.start() {
+            return None;
+        }
+    }
+}
diff --git a/src/main.rs b/src/main.rs
index 8a003d7..2c2359e 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -15,7 +15,8 @@ mod day13;
 mod day14;
 mod day15;
 mod day16;
+mod day17;
 
 fn main() {
-    day16::day16();
+    day17::day17();
 }