feat : solver + test

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

@@ -1,13 +1,10 @@
 package sudoku.solver;
 
 import sudoku.MultiDoku;
-import sudoku.MutableCell;
-import sudoku.constraint.IConstraint;
+import sudoku.Cell;
+import sudoku.io.SudokuPrinter;
 
-import java.util.ArrayList;
 import java.util.List;
-import java.util.Random;
-import java.util.Stack;
 
 public class Solver {
 
@@ -18,11 +15,15 @@ public class Solver {
      * @return boolean, true s'il est résolut ou false s'il ne l'est pas.
      */
     public static boolean solve(MultiDoku doku) {
-        MutableCell cellToFill = doku.getFirstEmptyMutableCell();
-        if (cellToFill == null) {
+        if (doku.isValid()) {
             return true;
         }
 
+        Cell cellToFill = doku.getFirstEmptyCell();
+        if (cellToFill == null) {
+            return false;
+        }
+
         List<Integer> possibleSymbols = doku.getPossibleSymbolsOfCell(cellToFill);
         if (possibleSymbols.isEmpty()) {
             return false;
@@ -30,7 +31,11 @@ public class Solver {
 
         for (int symbol : possibleSymbols) {
             cellToFill.setSymbolIndex(symbol);
-            return Solver.solve(doku);
+            if (Solver.solve(doku)) {
+                return true;
+            } else {
+                cellToFill.setSymbolIndex(Cell.NOSYMBOL);
+            }
         }
         return false;
     }