Introduce rectangles

src/main.rs

@@ -2,6 +2,7 @@ use rand::prelude::{StdRng, SliceRandom};
 use rand::{SeedableRng, Rng, thread_rng};
 
 pub const SIZE: usize = 16384;
+pub const HOUSE_RANGE: usize = 500;
 
 pub struct City {
     prices: Vec<u16>,
@@ -64,6 +65,26 @@ impl House {
     pub fn new(x: usize, y: usize) -> Self {
         House { x, y }
     }
+
+    pub fn range_rectangle(&self) -> Rectangle {
+        let top = if self.y <= HOUSE_RANGE { 0 } else { self.y - HOUSE_RANGE };
+        let bottom = if self.y >= SIZE - 1 - HOUSE_RANGE { SIZE - 1 } else { self.y + HOUSE_RANGE };
+        let left = if self.x <= HOUSE_RANGE { 0 } else { self.x - HOUSE_RANGE };
+        let right = if self.x >= SIZE - 1 - HOUSE_RANGE { SIZE - 1 } else { self.x + HOUSE_RANGE };
+        Rectangle {top, bottom, left, right}
+    }
+}
+
+/// Rectangle - a 2D range with inclusive bounds
+pub struct Rectangle {
+    /// The smaller x coordinate.
+    left: usize,
+    /// The bigger x coordinate.
+    right: usize,
+    /// The smaller y coordinate.
+    top: usize,
+    /// The bigger y coordinate.
+    bottom: usize,
 }
 
 struct HouseLayout<'a> {
@@ -87,8 +108,9 @@ impl<'a> HouseLayout<'a> {
     }
 
     pub fn add_house(&mut self, house: House) -> usize {
-        for y in (house.y as i32 - 500).max(0)..=(house.y as i32 + 500).min((SIZE - 1) as i32) {
+        let range_rect = house.range_rectangle();
-            for x in (house.x as i32 - 500).max(0)..=(house.x as i32 + 500).min((SIZE - 1) as i32) {
+        for y in range_rect.top..=range_rect.bottom {
+            for x in range_rect.left..=range_rect.right {
                 let index = y as usize * SIZE + x as usize;
 
                 if self.reachable[index] == 0 && self.city.is_house_xy(x as usize, y as usize) {
@@ -105,8 +127,9 @@ impl<'a> HouseLayout<'a> {
     pub fn remove_house(&mut self, index: usize) {
         let house = self.houses.swap_remove(index);
 
-        for y in (house.y as i32 - 500).max(0)..=(house.y as i32 + 500).min((SIZE - 1) as i32) {
+        let range_rect = house.range_rectangle();
-            for x in (house.x as i32 - 500).max(0)..=(house.x as i32 + 500).min((SIZE - 1) as i32) {
+        for y in range_rect.top..=range_rect.bottom {
+            for x in range_rect.left..=range_rect.right {
                 let index = y as usize * SIZE + x as usize;
 
                 self.reachable[index] -= 1;
@@ -134,8 +157,8 @@ impl<'a> HouseLayout<'a> {
 fn main() {
     let city = City::read_from_file("01.in");
 
-    const AROUND_RANGE: i32 = 200;
+    const AROUND_RANGE: i32 = 50;
-    const MAX_CANDIDATES: usize = 200;
+    const MAX_CANDIDATES: usize = 50;
     //const MAX_FAILED_ITERATIONS: usize = 50;
     println!("Params: AROUND_RANGE {}, MAX_CANDIDATES {}", AROUND_RANGE, MAX_CANDIDATES);
     eprintln!("Params: AROUND_RANGE {}, MAX_CANDIDATES {}", AROUND_RANGE, MAX_CANDIDATES);
@@ -247,8 +270,9 @@ fn main() {
 
 pub fn get_neighbors(city: &City, house: &House) -> Vec<House> {
     let mut neighbors = Vec::new();
-    for y in (house.y as i32 - 500).max(0)..=(house.y as i32 + 500).min((SIZE - 1) as i32) {
+    let range_rect = house.range_rectangle();
-        for x in (house.x as i32 - 500).max(0)..=(house.x as i32 + 500).min((SIZE - 1) as i32) {
+    for y in range_rect.top..=range_rect.bottom {
+        for x in range_rect.left..=range_rect.right {
             let house = House::new(x as usize, y as usize);
             if city.get_price(&house) > 0 {
                 neighbors.push(house);
@@ -282,8 +306,9 @@ fn is_valid(city: &City, houses: &Vec<House>) -> Option<u32> {
     for house in houses {
         assert!(city.prices[house.y * SIZE + house.x] > 0);
 
-        for y in (house.y as i32 - 500).max(0)..=(house.y as i32 + 500).min((SIZE - 1) as i32) {
+        let range_rect = house.range_rectangle();
-            for x in (house.x as i32 - 500).max(0)..=(house.x as i32 + 500).min((SIZE - 1) as i32) {
+        for y in range_rect.top..=range_rect.bottom {
+            for x in range_rect.left..=range_rect.right {
                 reachable[y as usize * SIZE + x as usize] = true;
             }
         }
@@ -300,3 +325,38 @@ fn is_valid(city: &City, houses: &Vec<House>) -> Option<u32> {
 
     Some(price)
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn house_rectangle_at_min() {
+        let house = House::new(0, 0);
+        let rect = house.range_rectangle();
+        assert_eq!(rect.top, 0);
+        assert_eq!(rect.left, 0);
+        assert_eq!(rect.right, HOUSE_RANGE);
+        assert_eq!(rect.bottom, HOUSE_RANGE);
+    }
+
+    #[test]
+    fn house_rectangle_at_max() {
+        let house = House::new(SIZE - 1, SIZE - 1);
+        let rect = house.range_rectangle();
+        assert_eq!(rect.top, SIZE - 1 - HOUSE_RANGE);
+        assert_eq!(rect.left, SIZE - 1 - HOUSE_RANGE);
+        assert_eq!(rect.right, SIZE - 1);
+        assert_eq!(rect.bottom, SIZE - 1);
+    }
+
+    #[test]
+    fn house_rect_in_middle() {
+        let house = House::new(SIZE / 2, SIZE / 2);
+        let rect = house.range_rectangle();
+        assert_eq!(rect.top, house.y - HOUSE_RANGE);
+        assert_eq!(rect.left, house.x - HOUSE_RANGE);
+        assert_eq!(rect.right, house.x + HOUSE_RANGE);
+        assert_eq!(rect.bottom, house.y + HOUSE_RANGE);
+    }
+}