mark [2] && mark [0]!= «»)

      {

      // we have a winner

      winner = mark [0];

      for (int j = 0; j <3; j++)

      boxArray[boxNumber[j]].BackColor =

      Color.Red;

      }

      }

      return (winner);

      }

      private void ComputerTurn ()

      {

      int selectedBox;

      int i, n;

      int j, k;

      String computerMark, playerMark, markToFind;

      int [] boxNumber = new int [3];

      String [] mark = new String [3];

      int emptyBox;

      int [] bestMoves = {4, 0, 2, 6, 8, 1, 3, 5, 7};

      if (rdoRandom.Checked)

      {

      // random logic

      // put mark in Nth available square

      n = myRandom.Next (9 – numberClicks) +1;

      i = 0;

      for (selectedBox = 0; selectedBox <9;

      selectedBox++)

      {

      if (boxArray [selectedBox].Text == «»)

      i++;

      if (i == n)

      break;

      }

      // put mark in SelectedBox

      lblBox_Click (boxArray [selectedBox], null);

      }

      else

      {

      // smart computer

      // determine who has what mark

      if (rdoComputerFirst.Checked)

      {

      computerMark = «X»;

      playerMark = «O»;

      }

      else

      {

      computerMark = «O»;

      playerMark = «X»;

      }

      // Step 1 (K = 1) – check for win —

      // see if two boxes hold

      // computer mark and one is empty

      // Step 2 (K = 2) – check for block —

      // see if two boxes hold

      // player mark and one is empty

      for (k = 1; k <= 2; k++)

      {

      if (k == 1)

      markToFind = computerMark;

      else

      markToFind = playerMark;

      for (i = 0; i <8; i++)

      {

      n = 0;

      emptyBox = 0;

      for (j = 0; j <3; j++)

      {

      boxNumber [j] = Convert.ToInt32 (

      possibleWins[i][j].ToString ());

      mark [j] = boxArray [boxNumber [j]].Text;

      if (mark [j] == markToFind)

      n++;

      else if (mark [j] == «»)

      emptyBox = boxNumber [j];

      }

      if (n == 2 && emptyBox!= 0)

      {

      // mark empty box to win (K = 1) or

      // block (K = 2)

      lblBox_Click (boxArray [emptyBox], null);

      return;

      }

      }

      }

      // Step 3 – find next best move

      for (i = 0; i <9; i++)

      {

      if (boxArray [bestMoves [i]].Text == «»)

      {

      lblBox_Click (boxArray [bestMoves [i]], null);

      return;

      }

      }

      }

      }