max connected regions

Author: Dhananjay Nagargoje

Diff for: src/main/java/problems/ongraph/MatrixConnectedRegions.java

@@ -0,0 +1,35 @@
+package problems.ongraph;
+
+import java.util.List;
+
+
+public class MatrixConnectedRegions {
+
+    final static int[][] SHIFT = {{0, 1}, {1, 0}, {0, -1}, {-1, 0}};
+
+
+    public static void flipColor(int x, int y, List<List<Boolean>> image) {
+        boolean currentColor = image.get(x).get(y);
+        paint(image, currentColor, x, y);
+        return;
+    }
+
+    private static void paint(List<List<Boolean>> image, boolean currentColor, int x, int y) {
+
+        image.get(x).set(y, !currentColor);
+        for (int a[] : SHIFT) {
+            if (isFeasible(image, x + a[0], y + a[1], currentColor)) {
+                paint(image, currentColor, x + a[0], y + a[1]);
+            }
+        }
+    }
+
+    public static boolean isFeasible(List<List<Boolean>> image, int x, int y, boolean currentColor) {
+        return x >= 0 && x < image.size() && y >= 0
+                && y < image.get(x).size()
+                && image.get(x).get(y) == currentColor;
+
+    }
+
+
+}