public int checkWin(Individual player)
{
/*
* Checks whether a board has a winning state in it
* row, column or a diagonal streak of SIZE/2
*
* player == 1 --> 'X'
* player == 2 --> 'O'
* returned value of 0 means there is no winner and there are still blank locations to play
* returned value of -1 means the game ended as a draw
*/
// counter for a streak of player pieces
int count = 0;
// check rows
for (int i = 0; i < SIZE * SIZE; i++)
{
// encountered player piece --> increase counter
if (board[i] == player.getValue())
{
count++;
}
else // streak is broken --> reset the counter
{
count = 0;
}
// if the counter has sufficient streak, return the player as the winner
if (count == streak)
{
return(player.getValue()); // player won
}
// reached the end of a row (last column) --> reset the counter
if (i % SIZE == SIZE - 1)
{
count = 0;
}
}
// check columns
for (int i = 0, col = 0; i < SIZE * SIZE; i++)
{
/* col is a variable which represent the current column and is increased when starting a new column count
* board[col + (i%SIZE)*SIZE] example:
* 0 1 2
* ---------
* 0| 0 1 2
* 1| 3 4 5
* 2| 6 7 8
*
* for location 0, 3, 6 checking
* location 0: col=0 i=0 SIZE=3 --> col + (i%SIZE)*SIZE = 0 + (0%3)*3 = 0 + 0 = 0
* location 3: col=0 i=1 SIZE=3 --> col + (i%SIZE)*SIZE = 0 + (1%3)*3 = 0 + 3 = 3
* location 6: col=0 i=2 SIZE=3 --> col + (i%SIZE)*SIZE = 0 + (2%3)*3 = 0 + 6 = 6
*
* for location 1, 4, 7 checking
* location 0: col=1 i=3 SIZE=3 --> col + (i%SIZE)*SIZE = 1 + (3%3)*3 = 1 + 0 = 1
* location 3: col=1 i=4 SIZE=3 --> col + (i%SIZE)*SIZE = 1 + (4%3)*3 = 1 + 3 = 3
* location 6: col=1 i=5 SIZE=3 --> col + (i%SIZE)*SIZE = 1 + (5%3)*3 = 1 + 6 = 6
*
* for location 2, 5, 8 checking
* location 0: col=2 i=6 SIZE=3 --> col + (i%SIZE)*SIZE = 2 + (6%3)*3 = 2 + 0 = 2
* location 3: col=2 i=7 SIZE=3 --> col + (i%SIZE)*SIZE = 2 + (7%3)*3 = 2 + 3 = 5
* location 6: col=2 i=8 SIZE=3 --> col + (i%SIZE)*SIZE = 2 + (8%3)*3 = 2 + 6 = 8
*
*/
// encountered player piece --> increase counter
if (board[col + (i % SIZE) * SIZE] == player.getValue())
{
count++;
}
else // streak is broken --> reset the counter
{
count = 0;
}
// if the counter has sufficient streak, return the player as the winner
if (count == streak)
{
return(player.getValue()); // player won
}
// reached the end of a column (last row) --> reset the counter
if (i % SIZE == SIZE - 1)
{
count = 0;
// only increase col variable after the first iteration (the above 'if' is invoked at i==0)
if (i > 0)
{
col++;
}
}
}
// check Left To Right diagonals from top to bottom (main diagonals)
for (int i = 0; i < SIZE * SIZE; i++)
{
// for each iteration of i, reset the counter
count = 0;
// start at i and iterate to the last index
// increment j with SIZE+1
// (+SIZE will result in getting the next row, +1 will result in one index to the right)
for (int j = i; j < SIZE * SIZE; j += SIZE + 1)
{
// count player pieces
if (board[j] == player.getValue())
{
count++;
}
else // reset the counter if the streak is broken
{
count = 0;
}
// check if the count streak is sufficient for a win
if (count == streak)
{
return(player.getValue());
}
// if j is out of bound of the array index
// or reached the right border (j % SIZE == SIZE-1), break the loop
if (j >= SIZE * SIZE || j % SIZE == SIZE - 1)
{
break;
}
}
}
// check Left To Right diagonals from bottom to top (secondary diagonals)
// start at the end of the board (last index) and go backward until reaching 0
for (int i = SIZE * SIZE - 1; i >= 0; i--)
{
// for each iteration of i, reset the counter
count = 0;
// start at i and iterate to the last index
// decrement j with SIZE-1
// (-SIZE will result in getting the previous row, -1 will result in one index to the left)
for (int j = i; j > 0; j -= (SIZE - 1))
{
// count player pieces
if (board[j] == player.getValue())
{
count++;
}
else // reset the counter if the streak is broken
{
count = 0;
}
// check if the count streak is sufficient for a win
if (count == streak)
{
return(player.getValue());
}
// if j is out of bound of the array index
// or reached the right border (j % SIZE == 0), break the loop
if (j < 0 || j % SIZE == SIZE - 1)
{
break;
}
}
}
// check draw
for (int i = 0; i < SIZE * SIZE; i++)
{
// if encountered a blank location, return 0 meaning the game can still be played
if (board[i] == 0)
{
return(0);
}
}
// none of the above returns invoked --> game ended as a draw
return(-1);
}