Submission for tic tac toe lab.

What I changed
I completed checkpoints 1-3. I would have submitted all three separately, but a bug prohibited my initial submissions.
I also started working on the nim section of the lab.

Why I changed it
I made these changes in order to make a functions tic tac toe and nim game.

Estimate for remaining time to finish assignment: 15 minutes

ttt/game.py

@@ -58,4 +58,22 @@ class TTTGame:
 
     def check_winner(self, state, symbol):
         "Checks whether the player with `symbol` has won the game."
-        return False
+        board = state["board"]
+        if board[0] == symbol and board[1] == symbol and board[2] == symbol:
+            return True
+        elif board[3] == symbol and board[4] == symbol and board[5] == symbol:
+            return True
+        elif board[6] == symbol and board[7] == symbol and board[8] == symbol:
+            return True
+        elif board[0] == symbol and board[3] == symbol and board[6] == symbol:
+            return True
+        elif board[1] == symbol and board[4] == symbol and board[7] == symbol:
+            return True
+        elif board[2] == symbol and board[5] == symbol and board[8] == symbol:
+            return True
+        elif board[0] == symbol and board[4] == symbol and board[8] == symbol:
+            return True
+        elif board[2] == symbol and board[4] == symbol and board[6] == symbol:
+            return True
+        else:
+            return False

ttt/player.py

@@ -1,5 +1,6 @@
 from click import Choice, prompt
 from strategy.random_strategy import RandomStrategy
+from strategy.lookahead_strategy import LookaheadStrategy
 from ttt.game import TTTGame
 import random
 
@@ -24,7 +25,7 @@ class TTTComputerPlayer:
     def __init__(self, name):
         "Sets up the player."
         self.name = name
-        self.strategy = RandomStrategy(TTTGame())
+        self.strategy = LookaheadStrategy(TTTGame(), deterministic=False)
 
     def choose_action(self, state):
         "Chooses a random move from the moves available."