Add ground check

day22/src/day22.rs

@@ -33,12 +33,6 @@ struct Vec3 {
  z: i32,
 }
 
-impl Vec3 {
- fn new(x: i32, y: i32, z: i32) -> Self {
- Self { x, y, z }
- }
-}
-
 impl Add<Vec3> for Vec3 {
  type Output = Self;
 
@@ -83,8 +77,9 @@ struct Brick {
 }
 
 impl Brick {
- fn fall(&self) {
- todo!()
+ fn fall(&self) -> Self {
+ let delta = Vec3 { x: 0, y: 0, z: -1 };
+ Self { start: self.start + delta, end: self.end + delta }
  }
 
  fn x_range(&self) -> RangeInclusive<i32> { self.start.x..=self.end.x }
@@ -99,6 +94,11 @@ impl Brick {
 
  fn z_aligned(&self) -> bool { self.start.x == self.end.x && self.start.y == self.end.y }
 
+ fn on_ground(&self) -> bool {
+ assert!(self.start.z >= 0 && self.end.z >= 0);
+ self.start.z == 1 || self.end.z == 1
+ }
+
  fn collides_with(&self, rhs: &Self) -> bool {
  (self.x_aligned() && rhs.x_aligned() && intersects(self.x_range(), rhs.x_range()))
  || (self.y_aligned() && rhs.y_aligned() && intersects(self.y_range(), rhs.y_range()))
@@ -125,7 +125,7 @@ impl Board {
  self.bricks
  .iter()
  .filter(|b| b.id != brick.id)
- .any(|b| b.collides_with(&brick.value))
+ .any(|b| b.on_ground() || b.collides_with(&brick.value))
  }
 
  fn step(&mut self) {