/* 判断一个皇后的位置是否安全 */
bool is_safe(int a[],position k,int col)
{
for(int i = 0;i <= col-1;++i){
if( is_same_row(a[i],k) || is_same_diagonal(a[i],i,k,col))
return false;
}
return true;
}
/* Requirement 6 - tests to see whether a move is valid or not */
BOOLEAN is_valid_move(struct move move, enum cell_contents board[][BOARD_WIDTH], enum move_validity *move_validity)
{
struct position jump_pos;
/* check both positions are valid */
if (!is_valid(move.start.x, move.start.y, board))
{
if (move_validity != NULL) *move_validity = INVALID_START_POSITION;
return FALSE;
}
if (!is_valid(move.end.x, move.end.y, board))
{
if (move_validity != NULL) *move_validity = INVALID_END_POSITION;
return FALSE;
}
/* check start is peg and end is hole */
if (!is_peg(move.start.x, move.start.y, board))
{
if (move_validity != NULL) *move_validity = START_NOT_PEG;
return FALSE;
}
if (!is_hole(move.end.x, move.end.y, board))
{
if (move_validity != NULL) *move_validity = END_NOT_HOLE;
return FALSE;
}
/* check positions are on the same row/column and separated by 1 cell */
if (!is_same_row(move.start, move.end, 2) && !is_same_column(move.start, move.end, 2))
{
if (move_validity != NULL) *move_validity = NOT_SAME_ROW_COLUMN;
return FALSE;
}
/* final check: there is a peg in between the positions */
jump_pos = get_jumped_position(move.start, move.end, board);
if (board[jump_pos.y][jump_pos.x] == PEG)
{
if (move_validity != NULL) *move_validity = VALID;
return TRUE;
}
else
{
if (move_validity != NULL) *move_validity = NO_PEG_TO_JUMP;
return FALSE;
}
}
/* returns the position between 2 positions, this function makes the assumption
that is_valid_move() has been passed */
struct position get_jumped_position(struct position p1, struct position p2, enum cell_contents board[][BOARD_HEIGHT])
{
struct position pos;
pos.x = p1.x;
pos.y = p1.y;
if (is_same_row(p1, p2, 2))
{
if (p1.y > p2.y)
pos.y = p1.y - 1;
else
pos.y = p1.y + 1;
}
else if (is_same_column(p1, p2, 2))
{
if (p1.x > p2.x)
pos.x = p1.x - 1;
else
pos.x = p1.x + 1;
}
return pos;
}
