Method playTicTacToe_minimax

code/main/ATree.ts:186–236

(board: ATreeTicTacToeSign[][], playerSign: ATreeTicTacToeSign, depth: number = 2)

    }
    
    private playTicTacToe_minimax(board: ATreeTicTacToeSign[][], playerSign: ATreeTicTacToeSign, depth: number = 2): ATreeTicTacToeMinimaxReturnValue{
        // Variables
        var tempBoard: ATreeTicTacToeSign[][]; // The temp board, used to simulate moves
        var currentScore: number; // Current score, used for calculations
        var returnValue: ATreeTicTacToeMinimaxReturnValue = new ATreeTicTacToeMinimaxReturnValue; // The return value, which contains the best position and the best score
        var gameFull: boolean = true; // Used later to find out if the game is full or not
        
        // Set the initial best score, depending on the playerSign parameter
        if(playerSign == ATreeTicTacToeSign.O) // If the player sign is the squirrel
            returnValue.bestScore = -99999999;
        else // Else
            returnValue.bestScore = 99999999;
    
        // If the depth is > to 0 (this condition is needed to stop the iterating loop at some point)
        if(depth > 0){
            // Iterate over all the board
            for(var i = 1; i <= 3; i++){
                for(var j = 1; j <= 3; j++){
                    // If this cell is empty
                    if(board[i][j] == ATreeTicTacToeSign.NO_SIGN){
                        // We found at least one non-empty cell : the game isn't full
                        gameFull = false;
                        // Set the temp board from the real board
                        tempBoard = this.playTicTacToe_copyBoard(board);
                        // Try to play on this cell using the temp board
                        tempBoard[i][j] = playerSign;
                        if(playerSign == ATreeTicTacToeSign.O){  // If we're testing the squirrel
                            currentScore = this.playTicTacToe_minimax(tempBoard, ATreeTicTacToeSign.X, depth - 1).bestScore;
                            if(returnValue.bestScore <= currentScore){
                                returnValue.bestScore = currentScore;
                                returnValue.bestPosition = new Pos(i, j);
                            }
                        }
                        else{ // Else, we're testing the player
                            currentScore = this.playTicTacToe_minimax(tempBoard, ATreeTicTacToeSign.O, depth - 1).bestScore;
                            if(returnValue.bestScore >= currentScore){
                                returnValue.bestScore = currentScore;
                                returnValue.bestPosition = new Pos(i, j);
                            }
                        }
                    }
                }
            }
            // If the game seems full, we calculate the best score too
            if(gameFull) returnValue.bestScore = this.playTicTacToe_evaluateBoard(board);
        }
        else returnValue.bestScore = this.playTicTacToe_evaluateBoard(board);
        
        // Return the return value (best position found + the score)
        return returnValue;
    }
    
    private playTicTacToe_testEndGameConditions(): boolean{
        // Variables