From 4b1980159492247caf55d94af68c8c04b8d035e5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ji=C5=99=C3=AD=20Sejkora?= <sejsel@sejsel.cz>
Date: Sun, 21 Feb 2021 00:12:08 +0100
Subject: [PATCH] Add an option to merge first before moving single houses

(seems to be fairly useless and it's slower)
---
 src/main.rs             |  2 +-
 src/optimization.rs     | 43 +++++++++++++++++++++++++----------------
 src/optimize-subcity.rs |  2 +-
 3 files changed, 28 insertions(+), 19 deletions(-)

diff --git a/src/main.rs b/src/main.rs
index 1e2161a..417bd7d 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -52,7 +52,7 @@ fn main() {
         //populate_from_saved_layout(&mut layout, &best_layout);
         //eprintln!("Finished loading DB layout ID {}, price: {}, houses: {}", best_layout.id(), layout.price(), layout.houses().len());
 
-        optimization::iterate_improvements(&mut layout, &mut rng, true);
+        optimization::iterate_improvements(&mut layout, &mut rng, true, START_WITH_MERGE);
         dump_layout(&layout, &mut best_price, seed);
         db.add_layout(&layout.houses(), true).expect("Failed to insert into DB");
     }
diff --git a/src/optimization.rs b/src/optimization.rs
index 67a12ba..ff7e295 100644
--- a/src/optimization.rs
+++ b/src/optimization.rs
@@ -8,7 +8,7 @@ pub enum RectangleSearchError {
     Unsatisfiable,
 }
 
-pub fn iterate_improvements(mut layout: &mut HouseLayout, mut rng: &mut StdRng, print_progress: bool) {
+pub fn iterate_improvements(mut layout: &mut HouseLayout, mut rng: &mut StdRng, print_progress: bool, merge_first: bool) -> bool {
     #[derive(Eq, PartialEq)]
     enum LastStep {
         None,
@@ -16,17 +16,25 @@ pub fn iterate_improvements(mut layout: &mut HouseLayout, mut rng: &mut StdRng,
         MergingPairs,
     }
 
+    let mut improved = false;
+
+    let mut first_iteration = true;
     let mut last_improved_step = LastStep::None;
     loop {
-        if last_improved_step == LastStep::MovingIndividual { break; }
-        if print_progress {
-            eprintln!("Starting moving individual houses...");
-        }
-        if improve_move_individual_houses(&mut layout, &mut rng) {
-            last_improved_step = LastStep::MovingIndividual;
-        }
-        if print_progress {
-            eprintln!("Finished moving individual houses...");
+        if merge_first && first_iteration {
+            first_iteration = false;
+        } else {
+            if last_improved_step == LastStep::MovingIndividual { break; }
+            if print_progress {
+                eprintln!("Starting moving individual houses...");
+            }
+            if improve_move_individual_houses(&mut layout, &mut rng) {
+                last_improved_step = LastStep::MovingIndividual;
+                improved = true;
+            }
+            if print_progress {
+                eprintln!("Finished moving individual houses...");
+            }
         }
 
         if last_improved_step == LastStep::MergingPairs { break; }
@@ -35,18 +43,15 @@ pub fn iterate_improvements(mut layout: &mut HouseLayout, mut rng: &mut StdRng,
         }
         if improve_merge_pairwise(&mut layout, print_progress) {
             last_improved_step = LastStep::MergingPairs;
+            improved = true;
         }
         if print_progress {
             eprintln!("Finished pairwise house merge");
         }
-        //eprintln!("Starting pairwise house move...");
-        //if optimization::improve_move_houses_pairwise(&mut layout) {
-        //    dump_layout(&layout, &mut best_price, seed);
-        //    improved = true;
-        //}
-        //eprintln!("Finished pairwise house move");
         if last_improved_step == LastStep::None { break; }
     }
+
+    improved
 }
 
 fn get_valid_move_rectangle_multiple(layout: &HouseLayout, houses: &Vec<House>) -> Result<Rectangle, RectangleSearchError> {
@@ -229,6 +234,8 @@ pub fn improve_merge_pairwise(layout: &mut HouseLayout, print_progress: bool) ->
         // We instead go through the houses repeatedly and remember which pairs we have already
         // tried by hashing their values because they can and do move throughout the layout Vec
         // as it's being modified.
+        // TODO: This may lead to some pairs still being mergeable thanks to another merge
+        //       that happened before.
         let mut checked = HashSet::new();
 
         let mut loop_improved = false;
@@ -277,7 +284,9 @@ pub fn improve_merge_pairwise(layout: &mut HouseLayout, print_progress: bool) ->
                                 }
                             }
                         }
-                        Err(RectangleSearchError::Useless) => eprintln!("Found useless pair of houses, not solving!"),
+                        Err(RectangleSearchError::Useless) => {
+                            //eprintln!("Found useless pair of houses, not solving!")
+                        },
                         Err(RectangleSearchError::Unsatisfiable) => {}
                     }
                 }
diff --git a/src/optimize-subcity.rs b/src/optimize-subcity.rs
index 5fddf01..c45509b 100644
--- a/src/optimize-subcity.rs
+++ b/src/optimize-subcity.rs
@@ -113,7 +113,7 @@ fn main() {
             //eprintln!("Starting random population {}", i);
             population::populate_random(&mut layout, &mut rng);
             //eprintln!("Finished random init {}, price: {}, houses: {}", i, layout.price(), layout.houses().len());
-            optimization::iterate_improvements(&mut layout, &mut rng, false);
+            optimization::iterate_improvements(&mut layout, &mut rng, false, false);
             //eprintln!("Finished iterated improvements {}, price: {}, houses: {}", i, layout.price(), layout.houses().len());
             layout.houses().clone()
         }));