that was a long session. i think minimax with alpha beta pruning works nowgit add .!

main.py

@@ -72,6 +72,122 @@ def checkWin(board, player):
             if all(board[col + i][row - i] == player for i in range(winCount)):
                 return [(col + i, row - i) for i in range(winCount)]
 
+def isTerminalNode(board):
+    if checkWin(board, 'R'):
+        return "WinX"
+    elif checkWin(board, 'Y'):
+        return "WinY"
+
+    if all('O' not in col for col in board):
+        return "Draw"
+
+    return False
+
+def evalWindow(window, player):
+    opponent = 'Y' if player == 'R' else 'R'
+
+    player_count = window.count(player)
+    opponent_count = window.count(opponent)
+    empty_count = window.count('O')
+
+    score = 0
+    if player_count == 4:
+        score += 100
+    elif player_count == 3 and empty_count == 1:
+        score += 5
+    elif player_count == 2 and empty_count == 2:
+        score += 2
+    
+    if opponent_count == 3 and empty_count == 1:
+        score -= 4
+    
+    return score
+
+def evalPositionForPlayer(board, player):
+    score = 0
+
+    # Score center column
+    center_col = len(board) // 2
+    center_array = board[center_col]
+    center_count = center_array.count(player)
+    score += center_count * 3
+
+    # Score Horizontal
+    for row in range(len(board[0])):
+        row_array = [board[col][row] for col in range(len(board))]
+        for col in range(len(board) - 3):
+            window = row_array[col:col+4]
+            score += evalWindow(window, player)
+
+    # Score Vertical
+    for col in range(len(board)):
+        col_array = board[col]
+        for row in range(len(board[col]) - 3):
+            window = col_array[row:row+4]
+            score += evalWindow(window, player)
+
+    # Score positive diagonals
+    for col in range(len(board) - 3):
+        for row in range(len(board[0]) - 3):
+            window = [board[col+i][row+i] for i in range(4)]
+            score += evalWindow(window, player)
+
+    # Score negative diagonals
+    for col in range(len(board) - 3):
+        for row in range(3, len(board[0])):
+            window = [board[col+i][row-i] for i in range(4)]
+            score += evalWindow(window, player)
+
+    return score
+
+def evalPosition(board):
+    red_score = evalPositionForPlayer(board, 'R')
+    yellow_score = evalPositionForPlayer(board, 'Y')
+    return red_score - yellow_score
+
+def minimax(board, depth, alpha, beta, maximisingPlayer):
+    isTerminal = isTerminalNode(board)
+
+    if isTerminal:
+        if isTerminal == "WinX":  # Red wins
+            return float('inf')
+        elif isTerminal == "WinY":  # Yellow wins
+            return float('-inf')
+        elif isTerminal == "Draw":
+            return 0
+
+    allowedMoves = [i for i, col in enumerate(board) if 'O' in col]
+
+    if depth == 0 or not allowedMoves:
+        return evalPosition(board)
+
+    if maximisingPlayer:
+        maxEval = float('-inf')
+        for move in allowedMoves:
+            newPosition = [col.copy() for col in board]
+            tile = newPosition[move].index("O")
+            newPosition[move][tile] = 'R'
+
+            evaluation = minimax(newPosition, depth - 1, alpha, beta, False)
+            maxEval = max(maxEval, evaluation)
+            alpha = max(alpha, evaluation)
+            if beta <= alpha:
+                break
+        return maxEval
+    else:
+        minEval = float('inf')
+        for move in allowedMoves:
+            newPosition = [col.copy() for col in board]
+            tile = newPosition[move].index("O")
+            newPosition[move][tile] = 'Y'
+
+            evaluation = minimax(newPosition, depth - 1, alpha, beta, True)
+            minEval = min(minEval, evaluation)
+            beta = min(beta, evaluation)
+            if beta <= alpha:
+                break
+        return minEval
+
 # ===========================
 # |  Player move providers  |
 # ===========================
@@ -79,36 +195,77 @@ def local_move_provider(player, board):
     col = getIntInput(f"{colourTile(player)} where do you want to drop your tile? 1-7.\n>>> ", board) - 1
     return col
 
-def cpu_move_provider(player, board):
-    col = 0
-    def other_player_gonna_win(my_move: int|None = None) -> int|bool:
-        if my_move == None: my_move = col
-        my_board = deepcopy(board)
-        my_board[my_move][my_board[my_move].index('O')] = player
+# def cpu_move_provider(player, board):
+#     col = 0
+#     def other_player_gonna_win(my_move: int|None = None) -> int|bool:
+#         if my_move == None: my_move = col
+#         my_board = deepcopy(board)
+#         my_board[my_move][my_board[my_move].index('O')] = player
         
-        other_p = 'Y' if player == 'R' else 'R'
-        for other_p_col in range(len(my_board)):
-            if 'O' not in my_board[other_p_col]:
-                continue
+#         other_p = 'Y' if player == 'R' else 'R'
+#         for other_p_col in range(len(my_board)):
+#             if 'O' not in my_board[other_p_col]:
+#                 continue
 
-            new_board = deepcopy(my_board)
-            new_board[other_p_col][new_board[other_p_col].index('O')] = other_p
-            if checkWin(new_board, other_p) != None:
-                return other_p_col
-        return False
+#             new_board = deepcopy(my_board)
+#             new_board[other_p_col][new_board[other_p_col].index('O')] = other_p
+#             if checkWin(new_board, other_p) != None:
+#                 return other_p_col
+#         return False
     
-    # Start with a random move
-    col = random.randint(0,6)
-    while not any([t == 'O' for t in board[col]]):
-        col += 1
-        if col == 7: col = 0
-    
-    # Prevent other player winning 1 move deep
-    if other_player_gonna_win():
-        col = other_player_gonna_win()
+#     def im_gonna_win() -> int|bool:
+#         for possible_col in range(len(my_board)):
+#             if 'O' not in my_board[other_p_col]:
+#                 continue
 
-    time.sleep((random.random()*0.5)+0.25)  # Simulate thinking time
-    return col
+#             new_board = deepcopy(my_board)
+#             new_board[other_p_col][new_board[other_p_col].index('O')] = other_p
+#             if checkWin(new_board, other_p) != None:
+#                 return other_p_col
+#         return False
+    
+#     # Start with a random move
+#     col = random.randint(0,6)
+#     while not any([t == 'O' for t in board[col]]):
+#         col += 1
+#         if col == 7: col = 0
+    
+#     # Prevent other player winning 1 move deep
+#     if other_player_gonna_win():
+#         col = other_player_gonna_win()
+
+#     time.sleep((random.random()*0.5)+0.25)  # Simulate thinking time
+#     return col
+
+def cpu_move_provider(player, board):
+    allowedMoves = [i for i, col in enumerate(board) if 'O' in col]
+
+    best_score = float('-inf') if player == 'R' else float('inf')
+    best_move = None
+
+    search_depth = 5
+    maximising = True if player == 'R' else False
+
+    for move in allowedMoves:
+        newBoard = [col.copy() for col in board]
+        tile = newBoard[move].index('O')
+        newBoard[move][tile] = player
+
+        score = minimax(newBoard, search_depth - 1, float('-inf'), float('inf'), not maximising)  # because next move is opponent's turn
+
+        if player == 'R':
+            if score > best_score:
+                best_score = score
+                best_move = move
+        else:
+            if score < best_score:
+                best_score = score
+                best_move = move
+
+    if best_move is None:
+        best_move = random.choice(allowedMoves)
+
+    return best_move
 
 # ===========================
 # |      Main game loop     |
@@ -164,7 +321,7 @@ def play_lan_client():
 
 def play_vs_computer():
     # play_game(cpu_move_provider, local_move_provider)
-    play_game(cpu_move_provider, cpu_move_provider)
+    play_game(local_move_provider, cpu_move_provider)
 
 # ===========================
 # |           Menu          |