fix : MultiDoku.getCells

app/src/main/java/sudoku/constraint/ColumnConstraint.java

@@ -1,5 +1,6 @@
 package sudoku.constraint;
 
+import sudoku.structure.Cell;
 import sudoku.structure.Sudoku;
 
 public class ColumnConstraint implements IConstraint {
@@ -7,10 +8,12 @@ public class ColumnConstraint implements IConstraint {
 	@Override
 	public boolean canBePlaced(final Sudoku s, int x, int y, int newSymbolIndex) {
 		for (int i = 0; i < s.getSize(); i++) {
-			if (s.getCell(x, i).getSymbolIndex() == newSymbolIndex)
+			Cell cell = s.getCell(x, i);
+			int symbol = cell.getSymbolIndex();
+			if (symbol == newSymbolIndex) {
 				return false;
+			}
 		}
 		return true;
 	}
-
 }