Randomized improvements, finding best

Takes best close house to a random house

src/find_useless.rs

@@ -5,6 +5,8 @@ use main::{get_neighbors, House, City};
 mod main;
 
 fn main() {
+    // This is quite frankly useless
+
     let city = City::read_from_file("01.in");
     let bar = ProgressBar::new(city.get_house_count() as u64);
     bar.set_style(ProgressStyle::default_bar()

src/main.rs

@@ -15,7 +15,7 @@ impl City {
 
         for y in 0..SIZE {
             for x in 0..SIZE {
-                let price = (values[(y * SIZE + x) * 2] as u16) | ((values[(y * SIZE + x) * 2] as u16) << 8);
+                let price = (values[(y * SIZE + x) * 2] as u16) | ((values[(y * SIZE + x) * 2 + 1] as u16) << 8);
                 prices.push(price);
             }
         }
@@ -69,6 +69,7 @@ impl House {
 fn main() {
     let city = City::read_from_file("01.in");
 
+    let mut best_price: Option<u32> = None;
     loop {
         let seed: u64 = thread_rng().gen();
         eprintln!("Starting seed {}", seed);
@@ -106,39 +107,70 @@ fn main() {
                 break;
             }
         }
+
         let mut price = get_price(&city, &houses);
-        eprintln!("Finished randomized init, price: {}", price);
-        loop {
+        eprintln!("Finished random init, price: {}", price);
+
+        const AROUND_RANGE: i32 = 50;
+        const MAX_CANDIDATES: usize = 20;
+        const MAX_FAILED_ITERATIONS: usize = 50;
+
+        let mut failed_iterations = 0;
+        while failed_iterations < MAX_FAILED_ITERATIONS {
             let house = &houses.choose(&mut rng).unwrap();
-            let mut new_candidate: Option<House> = None;
-            for _ in 0..5000 {
-                let delta_x = rng.gen_range(-50..=50);
-                let delta_y = rng.gen_range(-50..=50);
-                let new_x = (house.x as i32 + delta_x).max(0).min(SIZE as i32 - 1) as usize;
-                let new_y = (house.y as i32 + delta_y).max(0).min(SIZE as i32 - 1) as usize;
-                if city.is_house_xy(new_x, new_y) && city.get_price_xy(new_x, new_y) < city.get_price(&house) {
-                    new_candidate = Some(House::new(new_x, new_y));
-                    break;
+            let mut new_candidates = Vec::new();
+            for delta_y in -AROUND_RANGE..=AROUND_RANGE {
+                for delta_x in -AROUND_RANGE..=AROUND_RANGE {
+                    let new_x = (house.x as i32 + delta_x).max(0).min(SIZE as i32 - 1) as usize;
+                    let new_y = (house.y as i32 + delta_y).max(0).min(SIZE as i32 - 1) as usize;
+                    if city.is_house_xy(new_x, new_y) && city.get_price_xy(new_x, new_y) < city.get_price(&house) {
+                        new_candidates.push(House::new(new_x, new_y));
+                    }
                 }
             }
 
-            if let Some(candidate) = new_candidate {
-                eprint!("Found candidate...");
-                let mut new_houses: Vec<_> = houses.to_vec().into_iter().filter(|h| &h != house).collect();
-                new_houses.push(candidate);
-                if let Some(new_price) = is_valid(&city, &new_houses) {
-                    let price_diff = new_price as i64 - price as i64;
-                    eprintln!(" candidate is valid, price diff: {}.", price_diff);
-                    eprintln!("New price: {}", new_price);
-                    price = new_price;
-                    houses = new_houses;
-                    print_houses(&houses);
-                } else {
-                    eprintln!(" candidate is invalid.");
-                }
-            } else {
+            new_candidates.sort_by(|a, b| city.get_price(&a).cmp(&city.get_price(&b)));
+            if new_candidates.len() == 0 {
                 eprintln!("Did not find candidate");
+            } else {
+                for (i, &candidate) in new_candidates.iter().enumerate() {
+                    if i > MAX_CANDIDATES {
+                        break;
+                    }
+
+                    eprint!("Found candidate {}...", i);
+                    let mut new_houses: Vec<_> = houses.to_vec().into_iter().filter(|h| &h != house).collect();
+                    new_houses.push(candidate);
+                    // TODO: This is_valid check could be way more efficient
+                    if let Some(new_price) = is_valid(&city, &new_houses) {
+                        let price_diff = new_price as i64 - price as i64;
+                        eprintln!(" candidate is valid, price diff: {}.", price_diff);
+                        eprintln!("Improved price: {}", new_price);
+                        price = new_price;
+                        houses = new_houses;
+                        failed_iterations = 0;
+                        break;
+                    } else {
+                        eprintln!(" candidate is invalid.");
+                    }
+                }
             }
+
+            // Successful iterations always break
+            failed_iterations += 1;
+        }
+
+        if best_price.is_none() || price < best_price.unwrap() {
+            best_price = Some(price);
+            eprintln!("Finished randomization, price: {}, new best, printing", price);
+            println!("Price {}, seed {}", price, seed);
+            print_houses(&houses);
+            println!();
+        } else {
+            eprintln!("Finished randomization, price: {}, printing", price);
+            println!("Price {}, seed {}", price, seed);
+            print_houses(&houses);
+            println!();
         }
     }
 }