From 9af499c58596e01244bc23d9b317b08e804cd79c Mon Sep 17 00:00:00 2001
From: Greg Hellings <greg.hellings@gmail.com>
Date: Tue, 15 Oct 2024 23:32:56 -0500
Subject: [PATCH] A slightly cleaner implementation of regions

---
 src/board.rs | 108 ++++++++++++++++++++++++++++++++++++---------------
 1 file changed, 77 insertions(+), 31 deletions(-)

diff --git a/src/board.rs b/src/board.rs
index 9f9b542..cef7401 100644
--- a/src/board.rs
+++ b/src/board.rs
@@ -1,30 +1,45 @@
 use crate::cell::{Cell, CellValue};
 use std::collections::HashSet;
 
+const REGION_SIZE: usize = 9;
+const SUB_REGION_SIZE: usize = 3;
+
 pub struct Board {
     cells: Vec<Vec<Cell>>,
-    regions: Vec<Region>,
+    squares: Vec<Region>,
+    rows: Vec<Region>,
+    cols: Vec<Region>,
 }
 
 impl Board {
     pub fn new() -> Board {
-        let mut rows = Vec::with_capacity(9);
-        for _ in 0..9 {
-            let mut col = Vec::with_capacity(9);
-            for _ in 0..9 {
+        let mut cells = Vec::with_capacity(REGION_SIZE);
+        for _ in 0..REGION_SIZE {
+            let mut col = Vec::with_capacity(REGION_SIZE);
+            for _ in 0..REGION_SIZE {
                 col.push(Cell::default());
             }
-            rows.push(col);
+            cells.push(col);
         }
-        let mut regions = Vec::with_capacity(9);
-        for x in 0..3 {
-            for y in 0..3 {
-                regions.push(Region::new(&Point(x, y)));
+        let mut squares = Vec::with_capacity(REGION_SIZE);
+        for x in 0..SUB_REGION_SIZE {
+            for y in 0..SUB_REGION_SIZE {
+                squares.push(Region::new_square(&Point(x, y)));
             }
         }
+        let mut rows = Vec::with_capacity(REGION_SIZE);
+        for x in 0..REGION_SIZE {
+            rows.push(Region::new_row(&Point(x, 0)));
+        }
+        let mut cols = Vec::with_capacity(REGION_SIZE);
+        for y in 0..REGION_SIZE {
+            cols.push(Region::new_col(&Point(0, y)));
+        }
         let board = Board {
-            cells: rows,
-            regions
+            cells,
+            squares,
+            rows,
+            cols
         };
         board
     }
@@ -35,25 +50,37 @@ impl Board {
 
     pub fn set_value(&mut self, point: &Point, value: CellValue) {
         self.cells[point.0][point.1].set_value(value);
-        self.update_row(point.0, value);
-        self.update_column(point.1, value);
-        self.update_region(point, value);
+        self.update_regions(point, value);
+    }
+    
+    pub fn update_regions(&mut self, point: &Point, value: CellValue) {
+        self.update_columns(point, value);
+        self.update_rows(point, value);
+        self.update_squares(point, value);
     }
 
-    pub fn update_row(&mut self, x: usize, value: CellValue) {
-        for i in self.cells[x].iter_mut() {
-            i.remove_candidate(value);
+    pub fn update_rows(&mut self, point: &Point, value: CellValue) {
+        for row in self.rows.iter_mut() {
+            if row.includes(point) {
+                for pt in row.iter_mut() {
+                    self.cells[pt.0][pt.1].remove_candidate(value);
+                }
+            }
         }
     }
 
-    pub fn update_column(&mut self, y: usize, value: CellValue) {
-        for i in self.cells.iter_mut() {
-            (*i)[y].remove_candidate(value);
+    pub fn update_columns(&mut self, point: &Point, value: CellValue) {
+        for col in self.cols.iter_mut() {
+            if col.includes(point) {
+                for pt in col.iter_mut() {
+                    self.cells[pt.0][pt.1].remove_candidate(value);
+                }
+            }
         }
     }
 
-    pub fn update_region(&mut self, point: &Point, value: CellValue) {
-        for i in self.regions.iter_mut() {
+    pub fn update_squares(&mut self, point: &Point, value: CellValue) {
+        for i in self.squares.iter_mut() {
             if i.includes(point) {
                 for pt in i.iter_mut() {
                     self.cells[pt.0][pt.1].remove_candidate(value);
@@ -75,27 +102,46 @@ pub struct Region {
 }
 
 impl Region {
-    pub fn new(start: &Point)-> Region {
-        let mut points = Vec::with_capacity(9);
-        for x in start.0..(start.0 + 3) {
-            for y in start.1..(start.1 + 3) {
+    pub fn new_square(start: &Point)-> Region {
+        let mut points = Vec::with_capacity(REGION_SIZE);
+        for x in start.0..(start.0 + SUB_REGION_SIZE) {
+            for y in start.1..(start.1 + SUB_REGION_SIZE) {
                 points.push(Point(x, y));
             }
         }
         Region {
-            points,
+            points,            
         }
     }
     
-    pub fn iter(&self) -> std::slice::Iter<Point> {
+    pub fn new_row(start: &Point) -> Region {
+        let mut points = Vec::with_capacity(REGION_SIZE);
+        for y in 0..REGION_SIZE {
+            points.push(Point(start.0, y));
+        }        
+
+        Region { points }
+    }
+    
+    pub fn new_col(start: &Point) -> Region {
+        let mut points = Vec::with_capacity(REGION_SIZE);
+        for x in 0..REGION_SIZE {
+            points.push(Point(x, start.1));
+        }
+        Region { points }
+    }
+}
+
+impl Region {
+    fn iter(&self) -> std::slice::Iter<Point> {
         self.points.iter()
     }
     
-    pub fn includes(&self, point: &Point) -> bool {
+    fn includes(&self, point: &Point) -> bool {
         self.points.contains(point)
     }
     
-    pub fn iter_mut(&mut self) -> std::slice::IterMut<Point> {
+    fn iter_mut(&mut self) -> std::slice::IterMut<Point> {
         self.points.iter_mut()
     }
 }