From 50ba53ff44cc91f2a080707593373d5650bfce17 Mon Sep 17 00:00:00 2001
From: Antonio Orta <60408336+19690ao@users.noreply.github.com>
Date: Fri, 29 Sep 2023 16:43:19 -0400
Subject: [PATCH] Region Based Changes (#559)

Co-authored-by: Hanson Gu <123511202+hansongu123@users.noreply.github.com>
---
 .../puzzle/nurikabe/NurikabeUtilities.java    | 63 +++++++++++++++++++
 .../rules/NoNumberContradictionRule.java      | 22 +++----
 2 files changed, 73 insertions(+), 12 deletions(-)

diff --git a/src/main/java/edu/rpi/legup/puzzle/nurikabe/NurikabeUtilities.java b/src/main/java/edu/rpi/legup/puzzle/nurikabe/NurikabeUtilities.java
index 34278ff9f..024cf6bb2 100644
--- a/src/main/java/edu/rpi/legup/puzzle/nurikabe/NurikabeUtilities.java
+++ b/src/main/java/edu/rpi/legup/puzzle/nurikabe/NurikabeUtilities.java
@@ -241,4 +241,67 @@ public static HashMap<NurikabeCell, Integer> getWhiteRegionMap(NurikabeBoard boa
         }
         return whiteRegionMap;
     }
+
+    /**
+     * Gets all the non-black cells connected to the given cell
+     *
+     * @param board nurikabe board
+     * @param center nurikabe cell
+     * @return a set of all white/numbered cells in the region
+     */
+    public static Set<NurikabeCell> getSurroundedRegionOf(NurikabeBoard board, NurikabeCell center) {
+        int width = board.getWidth();
+        int height = board.getHeight();
+
+        // Mark all the vertices as not visited(By default
+        // set as false)
+        Set<NurikabeCell> visited = new HashSet<>();
+
+        // Create a queue for BFS
+        LinkedList<NurikabeCell> queue = new LinkedList<>();
+
+        // Mark the current node as visited and enqueue it
+        visited.add(center);
+        queue.add(center);
+
+        // Set of cells in the current region
+        Set<NurikabeCell> connected = new HashSet<>();
+
+        while (queue.size() != 0) {
+            // Dequeue a vertex from queue and print it
+            // s is the source node in the graph
+            NurikabeCell s = queue.poll();
+            System.out.print(s + " ");
+
+            // Make a set of all adjacent squares
+            Set<NurikabeCell> adj = new HashSet<>();
+
+            Point loc = s.getLocation();
+            // First check if the side is on the board
+            if (loc.x >= 1) {
+                adj.add(board.getCell(loc.x - 1, loc.y));
+            }
+            if (loc.x < width - 1) {
+                adj.add(board.getCell(loc.x + 1, loc.y));
+            }
+            if (loc.y >= 1) {
+                adj.add(board.getCell(loc.x, loc.y - 1));
+            }
+            if (loc.y < height - 1) {
+                adj.add(board.getCell(loc.x, loc.y + 1));
+            }
+            // Get all adjacent vertices of the dequeued vertex s
+            // If a adjacent has not been visited, then mark it
+            // visited and enqueue it
+            for (NurikabeCell n : adj) {
+                if (!visited.contains(n) && n.getType() != NurikabeType.BLACK) {
+                    connected.add(n);
+                    visited.add(n);
+                    queue.add(n);
+                }
+            }
+        }
+
+        return connected;
+    }
 }
diff --git a/src/main/java/edu/rpi/legup/puzzle/nurikabe/rules/NoNumberContradictionRule.java b/src/main/java/edu/rpi/legup/puzzle/nurikabe/rules/NoNumberContradictionRule.java
index 06eb9d2eb..c2752da7a 100644
--- a/src/main/java/edu/rpi/legup/puzzle/nurikabe/rules/NoNumberContradictionRule.java
+++ b/src/main/java/edu/rpi/legup/puzzle/nurikabe/rules/NoNumberContradictionRule.java
@@ -42,20 +42,18 @@ public String checkContradictionAt(Board board, PuzzleElement puzzleElement) {
             return super.getInvalidUseOfRuleMessage() + ": " + this.INVALID_USE_MESSAGE;
         }
 
-//        If the transition creates a room of white cells with no number, a contradiction occurs.
-        DisjointSets<NurikabeCell> anotherRegion = NurikabeUtilities.getPossibleWhiteRegions(nurikabeBoard);
-        List<Set<NurikabeCell>> allsets = anotherRegion.getAllSets();
-        for (Set<NurikabeCell> s : allsets) {
-            boolean numberExists = false;
-            for (NurikabeCell c : s) {
-                if (c.getType() == NurikabeType.NUMBER) {
-                    numberExists = true;
-                }
-            }
-            if (!numberExists) {
-                return null;
+        Set<NurikabeCell> region = NurikabeUtilities.getSurroundedRegionOf(nurikabeBoard, cell);
+
+        boolean numberExists = false;
+        for (NurikabeCell c : region) {
+            if (c.getType() == NurikabeType.NUMBER) {
+                numberExists = true;
+                break;
             }
         }
+        if (!numberExists) {
+            return null;
+        }
         return super.getNoContradictionMessage() + ": " + this.NO_CONTRADICTION_MESSAGE;
     }