diff --git a/src/othello/Main.java b/src/othello/Main.java
index 654946f..3cfbef2 100644
--- a/src/othello/Main.java
+++ b/src/othello/Main.java
@@ -1,14 +1,14 @@
 package othello;
 
+import othello.players.NegamaxPlayer;
 import othello.players.Player;
-import othello.players.RandomPlayer;
 
 public class Main {
 
 
 	public static void main(String[] args) {
-		Player p1 = new RandomPlayer(10);
-		Player p2 = new RandomPlayer(10);
+		Player p1 = new NegamaxPlayer(4);
+		Player p2 = new NegamaxPlayer(4);
 		Player[][] board = initialize(p1, p2);
 		State game = new State(board, p1, p2);
 		System.out.println("joueur 1: " + p1);
diff --git a/src/othello/State.java b/src/othello/State.java
index fc5047d..818bc6d 100644
--- a/src/othello/State.java
+++ b/src/othello/State.java
@@ -59,7 +59,7 @@ public class State {
 	}
 	
 	public int getScore(Player player) {
-		return player == player1 ? n1 : n2;
+		return player == player1 ? (n1/(n1+n2)) : (n2/(n1+n2));
 	}
 
 	public Player getWinner() {
@@ -73,15 +73,18 @@ public class State {
 
 	public State play(Pair<Point,Point> move) {
 		State copy = this.copy();
-		copy.board[move.getRight().getY()][move.getRight().getX()] = copy.getCurrentPlayer();
-		if(move.getLeft().isJump(move.getRight(),copy.board)){
-			copy.board[move.getLeft().getY()][move.getLeft().getX()] = null;
-		}
-		for(int i = -1; i < 2; i++){
-			for(int z = -1; z < 2; z++){
-				try {
-					copy.board[move.getRight().getY() + i][move.getRight().getX() + z] = copy.getCurrentPlayer();
-				}catch (IndexOutOfBoundsException ignored) {}
+		if(move!=null) {
+			copy.board[move.getRight().getY()][move.getRight().getX()] = copy.currentPlayer;
+			if (move.getLeft().isJump(move.getRight(), copy.board)) {
+				copy.board[move.getLeft().getY()][move.getLeft().getX()] = null;
+			}
+			for (int i = -1; i < 2; i++) {
+				for (int z = -1; z < 2; z++) {
+					try {
+						copy.board[move.getRight().getY() + i][move.getRight().getX() + z] = copy.currentPlayer;
+					} catch (IndexOutOfBoundsException ignored) {
+					}
+				}
 			}
 		}
 		int ni = 0, nj = 0;
diff --git a/src/othello/players/NegamaxPlayer.java b/src/othello/players/NegamaxPlayer.java
index e26e8e8..0e68390 100644
--- a/src/othello/players/NegamaxPlayer.java
+++ b/src/othello/players/NegamaxPlayer.java
@@ -6,7 +6,6 @@ import othello.State;
 
 public class NegamaxPlayer extends Player {
 
-
     public NegamaxPlayer(int depth) {
         super(depth);
     }
@@ -16,9 +15,8 @@ public class NegamaxPlayer extends Player {
         int bestValue = Integer.MIN_VALUE;
         Pair<Point, Point> bestMove = null;
         for(Pair<Point, Point> move : game.getMove(game.getCurrentPlayer())) {
-            State nextState = game.copy();
-            nextState.play(move);
-            int value = -negamax(nextState, depth);
+            State nextState = game.play(move);
+            int value = -negamax(nextState, this.depth,Integer.MIN_VALUE,Integer.MAX_VALUE);
             if (value > bestValue) {
                 bestValue = value;
                 bestMove = move;
@@ -27,17 +25,29 @@ public class NegamaxPlayer extends Player {
         return bestMove;
     }
 
-    private Integer negamax(State game, int depth) {
-        if(depth == 0 || game.isOver()) {
-            return game.getScore(game.getCurrentPlayer());
+    private int negamax(State state, int depth,int alpha,int beta) {
+        if(depth == 0 || state.isOver()) {
+            return evaluate(state);
         }
-        int bestValue = Integer.MIN_VALUE;
-        for(Pair<Point, Point> move : game.getMove(game.getCurrentPlayer())) {
-            State nextState = game.copy();
-            bestValue = Math.max(bestValue,-negamax(nextState.play(move),depth-1));
-
+        else{
+            int m = Integer.MIN_VALUE;
+            for (Pair<Point, Point> move : state.getMove(state.getCurrentPlayer())) {
+                State nextState = state.play(move);
+                m= Math.max(m,-negamax(nextState,depth-1,alpha,beta));
+                alpha = Math.max(alpha, m);
+                if(alpha >= beta)
+                    break;
+            }
+            return m;
         }
-        return bestValue;
+    }
+    private int evaluate(State game){
+        Player winner = game.getWinner();
+        if(winner == null)
+            return 0;
+        else if(winner == game.getCurrentPlayer())
+            return 1;
+        return -1;
     }
 
 }