diff --git a/search/search.py b/search/search.py
index a65998a..d2b9aae 100644
--- a/search/search.py
+++ b/search/search.py
@@ -188,6 +188,7 @@ def uniformCostSearch(problem):
                     maFileEtat.push(succNoeudCourant,succCostChemin)
                     # Ajouter le nouveau chemin dans la file avec son cout
                     maFileChemin.push(listeDirections+[succDirection],succCostChemin)
+                # si noeud existant, mettre a jour le cout si meilleur 
                 elif (succNoeudCourant in [i[0] for i in maFileEtat.heap]):
                     maFileEtat.update(succNoeudCourant,succCostChemin)
         listeDirections = maFileChemin.pop()
@@ -240,6 +241,7 @@ def aStarSearch(problem, heuristic=nullHeuristic):
                     maFileEtat.push(succNoeudCourant,succCostChemin)
                     # Ajouter le nouveau chemin dans la file avec son cout
                     maFileChemin.push(listeDirections+[succDirection],succCostChemin)
+                # si noeud existant, mettre a jour le cout si meilleur    
                 elif (succNoeudCourant in [i[0] for i in maFileEtat.heap]):
                     maFileEtat.update(succNoeudCourant,succCostChemin)
         listeDirections = maFileChemin.pop()
diff --git a/search/searchAgents.py b/search/searchAgents.py
index 1d757b1..068b623 100644
--- a/search/searchAgents.py
+++ b/search/searchAgents.py
@@ -288,6 +288,8 @@ class CornersProblem(search.SearchProblem):
         # Please add any code here which you would like to use
         # in initializing the problem
         "*** YOUR CODE HERE ***"
+        self.cornerSet = {(1,1), (1,top), (right, 1), (right, top)}
+        self.defaultCost = 1
 
     def getStartState(self):
         """
@@ -295,14 +297,24 @@ class CornersProblem(search.SearchProblem):
         space)
         """
         "*** YOUR CODE HERE ***"
-        util.raiseNotDefined()
+        return (self.startingPosition,self.cornerSet)
 
     def isGoalState(self, state):
         """
         Returns whether this search state is a goal state of the problem.
         """
         "*** YOUR CODE HERE ***"
-        util.raiseNotDefined()
+        currentPosition, currentCornerSet = state
+        print "Validation du but a ", currentPosition, "Coins restants: ", currentCornerSet
+        # On atteint le but s'il reste un seul coin a atteindre, et que c'est l'etat actuel
+        if len(currentCornerSet)==1:
+            if currentPosition in currentCornerSet:
+                print "But atteint"
+                return True
+            else:
+                return False
+        else:
+            return False
 
     def getSuccessors(self, state):
         """
@@ -325,7 +337,20 @@ class CornersProblem(search.SearchProblem):
             #   hitsWall = self.walls[nextx][nexty]
 
             "*** YOUR CODE HERE ***"
-
+            currentPosition, currentCornerSet = state
+            x,y = currentPosition
+            dx, dy = Actions.directionToVector(action)
+            nextx, nexty = int(x + dx), int(y + dy)
+            nextPosition = (nextx, nexty)
+            hitsWall = self.walls[nextx][nexty]
+            if not hitsWall:
+                # vu que le set est une structure mutable, j'en fais une copie a chaque fois, 
+                # sinon elle reste modifiee dans la boucle
+                currentCornerSet2 = currentCornerSet.copy()
+                # Si la position est un coin, alors enlever de l'ensemble
+                currentCornerSet2.discard(currentPosition)
+                nextCornerState = (nextPosition,currentCornerSet2)            
+                successors.append((nextCornerState, action, self.defaultCost))
         self._expanded += 1 # DO NOT CHANGE
         return successors