MoveGenerator::MoveGenerator(HexBoard &board)
{
// retrieve all unoccupied cells on the board
board.GetCells(hcs, HEXBLANK);
// shuffle them to randomize them
std::random_shuffle(hcs.begin(), hcs.end());
// set cursor to beginning of sequence
cursor = 0;
}
void HexMC1Player::Move(HexBoard &board, HexColor turn, unsigned int &row, unsigned int &col)
{
clock_t tStart = clock();
const unsigned int nTrials = 1000;
// keep track of best play and best score
int bestScore = -1;
unsigned int bestPlay;
// obtain the currently open cells
HexCellSet hcs;
board.GetCells(hcs, HEXBLANK);
unsigned int nCells = hcs.size();
// shuffle cells to examine them in random order
shuffleVector(hcs, 0, nCells);
// precompute the order of moves during simulation
HexColor turns[2];
turns[0] = turn;
turns[1] = ((turn == HEXBLUE) ? HEXRED : HEXBLUE);
// now evaluate each cell in turn
for (unsigned int iCell = 0; iCell < nCells; iCell++)
{
// make a working copy of the cell set
HexCellSet hcsCopy(hcs);
// store away the current cell by swapping with last cell
swapEntries(hcsCopy, iCell, nCells - 1);
// run MC simulation
int nWins = 0;
for (unsigned int iTrial = 0; iTrial < nTrials; iTrial++)
{
// shuffle the first n-1 entries (keeping the current cell safely at the end)
// to randomize the order in which cells are played in simulation
shuffleVector(hcsCopy, 0, nCells-1);
// make a copy of the board to run simulated game
HexBoard boardCopy(board);
// alternate turns until board is full (until no more cells to play)
for (unsigned int iTurn = 0; iTurn < nCells; iTurn++)
{
// for the first move, play the cell currently under evaluation,
// which is stored at the end of the vector.
// for subsequent moves, play each cell in succession, starting from 0th cell
unsigned int thisMove = ((iTurn == 0) ? (nCells - 1) : (iTurn - 1));
HexColor thisColor = turns[iTurn % 2];
boardCopy.SetColor(hcsCopy[thisMove].row, hcsCopy[thisMove].col, thisColor);
}
// find out who won this simulated game
HexColor winner = boardCopy.Winner();
// if we won, update stats
if (winner == turn)
{
nWins++;
}
}
if (nWins > bestScore)
{
bestScore = nWins;
bestPlay = iCell;
if (nWins == nTrials)
{
// if this cell won all its trials, then play it
break;
}
}
}
// return the best play we found
clock_t tEnd = clock();
clock_t tElapsed = (tEnd - tStart) / CLOCKS_PER_SEC;
std::cout << "Time elapsed: " << tElapsed << "(secs) \n";
row = hcs[bestPlay].row;
col = hcs[bestPlay].col;
}
