feat coordinate

app/src/main/java/sudoku/MultiDoku.java

@@ -42,4 +42,20 @@ public class MultiDoku {
 		return mutableCells;
 	}
 
+	public void updateSymbolsPossibilities() throws Exception {
+		for (Sudoku sudoku : subGrids){
+			sudoku.updateSymbolsPossibilities();
+		}
+	}
+
+	@Override
+	public String toString() {
+		StringBuilder sb = new StringBuilder();
+		sb.append("Multidoku {");
+		for (Sudoku sudoku : subGrids){
+			sb.append("\n\t").append(sudoku.toString());
+		}
+		sb.append("\n}");
+		return sb.toString();
+	}
 }