works but i cant place pieces after

OOP_3B5_Project/src/backend/Board.java

@@ -269,8 +269,10 @@ public class Board {
     }
 	
 	public void undoLastMove() {
-		//TODO
-		
+		if (turnNb > 0) { // only if turnnb is positive
+            turnNb--; // decrease turnNb
+            pieces = boardHistory.get(turnNb); // replace the arraylist pieces with the one associated with last turn
+        }	
 	}
 
 	public Board(Board board) {