update clear function in multidoku + solver soolve

app/src/main/java/sudoku/MutableCell.java

@@ -21,13 +21,18 @@ public class MutableCell extends Cell{
 		this.symboleIndex = symboleIndex;
 	}
 
-	public void clear() {
+	/**
+	 * Remove the current symboleIndex and returns it
+	 * @return integer symboleIndex cleared
+	 */
+	public int clear() {
+		int i = this.symboleIndex;
 		setSymboleIndex(NOSYMBOLE);
+		return i;
 	}
 
-	public void clear(int indexSymbol) {
+	public void removeHint(int indexSymbol) {
 		hintsSymbolIndex.remove(indexSymbol);
-		this.clear();
 	}
 
 	public List<Integer> getHints() {

app/src/main/java/sudoku/solver/Solver.java

@@ -27,8 +27,8 @@ public class Solver {
             int indexCurrentCell = rand.nextInt(remainingCellsToCheck.size());
             MutableCell currentCell = remainingCellsToCheck.get(indexCurrentCell);
             if (currentCell.getHints().isEmpty()){
-                MutableCell modify = allMutableCells.get(stack.undo());
-                modify.clear(modify.getSymboleIndex());
+                MutableCell modify = stack.undo();
+                modify.removeHint(modify.clear());
             }