Flood fill in java

contents/flood_fill/code/java/flood_fill.java

@@ -0,0 +1,96 @@
+package code.java;
+import java.util.*;
+public class flood_fill {
+        static class Point{
+            int x;
+            int y;
+            public Point(int x,int y){
+                this.x = x;
+                this.y = y;
+            }
+        }
+        public static boolean inbound(int[][] grid, Point p){
+            int row = grid.length, col = grid[0].length;
+            return (p.x < 0 || p.x >= row || p.y < 0 || p.y >= col);
+        }
+        public static List<Point> find_neighbors(int[][] grid, Point p, int old_val, int new_val){
+            //north, south, east, west neighbors
+            List<Point> possible_neighbors = new ArrayList<>();
+            List<Point> neighbors = new ArrayList<>();
+            possible_neighbors.add(new Point(p.x,p.y + 1));
+            possible_neighbors.add(new Point(p.x,p.y - 1));
+            possible_neighbors.add(new Point(p.x - 1, p.y));
+            possible_neighbors.add(new Point(p.x + 1, p.y));
+            //exclude the neighbors that go out of bounds and should not be colored
+            for (Point possible_neighbor : possible_neighbors){
+                if(inbound(grid,possible_neighbor) && grid[possible_neighbor.x][possible_neighbor.y] == old_val){
+                    neighbors.add(possible_neighbor);
+                }
+            }
+            return neighbors;
+        }
+        public static void stack_fill(int[][] grid, Point p, int old_val, int new_val){
+            if (old_val == new_val) return;
+            Stack<Point> stack = new Stack<>();
+            stack.add(p);
+            while (!stack.empty()){
+                Point cur = stack.pop();
+                grid[cur.x][cur.y] = new_val;
+                for (Point neighbor : find_neighbors(grid, cur, old_val, new_val)){
+                    stack.add(neighbor);
+                }
+            }
+        }
+        public static void recursive_fill(int[][] grid, Point p, int old_val, int new_val){
+            if (old_val == new_val) return;
+            grid[p.x][p.y] = new_val;
+            for (Point neighbor : find_neighbors(grid, p, old_val, new_val)){
+                recursive_fill(grid, neighbor, old_val, new_val);
+            }
+        }
+        public static void queue_fill(int[][] grid, Point p, int old_val, int new_val){
+            if (old_val == new_val) return;
+            Queue<Point> queue = new ArrayDeque<>();
+            queue.add(p);
+            while (!queue.isEmpty()){
+                Point cur = queue.remove();
+                for (Point neighbor : find_neighbors(grid, cur, old_val, new_val)){
+                    grid[neighbor.x][neighbor.y] = new_val;
+                    queue.add(neighbor);
+                }
+            }
+        }
+        public static boolean isEqual(int[][] grid, int[][] solution){
+            for(int i = 0; i < grid.length; i++){
+                for(int j = 0; j < grid[0].length; j++) {
+                    if(grid[i][j] != solution[i][j]) return false;
+                }
+            }
+            return true;
+        }
+        public static void main(String[] args) {
+            Point start = new Point(0,0);
+            int[][] grid = {
+                {0, 0, 1, 0, 0},
+                {0, 0, 1, 0, 0},
+                {0, 0, 1, 0, 0},
+                {0, 0, 1, 0, 0},
+                {0, 0, 1, 0, 0}};
+
+            int[][] solution = {
+                {1, 1, 1, 0, 0},
+                {1, 1, 1, 0, 0},
+                {1, 1, 1, 0, 0},
+                {1, 1, 1, 0, 0},
+                {1, 1, 1, 0, 0}};
+
+           queue_fill(grid, start, 0, 1);
+           if(isEqual(grid, solution)) System.out.println("test pass");
+           stack_fill(grid, start, 0, 1);
+           if(isEqual(grid, solution)) System.out.println("test pass");
+           recursive_fill(grid, start, 0, 1);
+           if(isEqual(grid, solution)) System.out.println("test pass");
+        }
+}
+
+

contents/flood_fill/flood_fill.md

@@ -96,6 +96,8 @@ In code, this might look like this:
 [import:10-25, lang="python"](code/python/flood_fill.py)
 {% sample lang="coco" %}
 [import:15-20, lang="coconut"](code/coconut/flood_fill.coco)
+{% sample lang="java" %}
+[import:17-32, lang="java"](code/java/flood_fill.java)
 {% endmethod %}
 
 
@@ -118,6 +120,8 @@ In code, it might look like this:
 [import:55-63, lang="python"](code/python/flood_fill.py)
 {% sample lang="coco" %}
 [import:52-61, lang:"coconut"](code/coconut/flood_fill.coco)
+{% sample lang="java" %}
+[import:45-51, lang="java"](code/java/flood_fill.java)
 {% endmethod %}
 
 The above code continues recursing through available neighbors as long as neighbors exist, and this should work so long as we are adding the correct set of neighbors.
@@ -135,6 +139,8 @@ Additionally, it is possible to do the same type of traversal by managing a stac
 [import:27-36, lang="python"](code/python/flood_fill.py)
 {% sample lang="coco" %}
 [import:23-34, lang:"coconut"](code/coconut/flood_fill.coco)
+{% sample lang="java" %}
+[import:33-44, lang="java"](code/java/flood_fill.java)
 {% endmethod %}
 
 This is ultimately the same method of traversal as before; however, because we are managing our own data structure, there are a few distinct differences:
@@ -180,6 +186,8 @@ The code would look something like this:
 [import:38-53, lang="python"](code/python/flood_fill.py)
 {% sample lang="coco" %}
 [import:36-49, lang:"coconut"](code/coconut/flood_fill.coco)
+{% sample lang="java" %}
+[import:52-63, lang="java"](code/java/flood_fill.java)
 {% endmethod %}
 
 Now, there is a small trick in this code that must be considered to make sure it runs optimally.
@@ -264,6 +272,8 @@ After, we will fill in the left-hand side of the array to be all ones by choosin
 [import:, lang="python"](code/python/flood_fill.py)
 {% sample lang="coco" %}
 [import, lang="coconut"](code/coconut/flood_fill.coco)
+{% sample lang="java" %}
+[import, lang="java"](code/java/flood_fill.java)
 {% endmethod %}