/*
* Updates the board with a move. Assumes that the move is legal.
*/
void Board::doMove(Player p, Move m) {
if (m == MOVE_PASS)
return;
int x = getX(m);
int y = getY(m);
assert(pieces[index(x, y)] == EMPTY);
assert(chainID[index(x, y)] == 0);
pieces[index(x, y)] = p;
zobristKey ^= zobristTable[zobristIndex(p, x, y)];
Player victim = otherPlayer(p);
Stone east = pieces[index(x+1, y)];
Stone west = pieces[index(x-1, y)];
Stone north = pieces[index(x, y+1)];
Stone south = pieces[index(x, y-1)];
int connectionCount = (east == p) + (west == p) + (north == p) + (south == p);
// If the stone placed is a new chain
if (connectionCount == 0) {
// Record which chain this square is a part of
chainID[index(x, y)] = nextID;
// Add this chain to the list of chains
Chain *cargo = new Chain(p, nextID);
cargo->add(m);
cargo->liberties = 0;
if (east == EMPTY)
cargo->addLiberty(coordToMove(x+1, y));
if (west == EMPTY)
cargo->addLiberty(coordToMove(x-1, y));
if (north == EMPTY)
cargo->addLiberty(coordToMove(x, y+1));
if (south == EMPTY)
cargo->addLiberty(coordToMove(x, y-1));
chainList.add(cargo);
nextID++;
}
// If the stone placed is added to an existing chain
else if (connectionCount == 1) {
// Find the ID of the chain we are adding this stone to
int thisID;
if (east == p)
thisID = chainID[index(x+1, y)];
else if (west == p)
thisID = chainID[index(x-1, y)];
else if (north == p)
thisID = chainID[index(x, y+1)];
else
thisID = chainID[index(x, y-1)];
chainID[index(x, y)] = thisID;
Chain *node = nullptr;
searchChainsByID(node, thisID);
node->add(m);
// The new stone occupies a previous liberty, but adds on however many
// liberties it itself has
node->removeLiberty(node->findLiberty(m));
updateLiberty(node, x, y);
}
// If the stone possibly connects two existing chains
else {
int eastID = (east == p) * chainID[index(x+1, y)];
int westID = (west == p) * chainID[index(x-1, y)];
int northID = (north == p) * chainID[index(x, y+1)];
int southID = (south == p) * chainID[index(x, y-1)];
Chain *node = nullptr;
bool added = false;
if (eastID) {
chainID[index(x, y)] = eastID;
searchChainsByID(node, eastID);
node->add(m);
node->removeLiberty(node->findLiberty(m));
updateLiberty(node, x, y);
added = true;
}
if (westID) {
if (added) {
// If two stones from the same chain are adjacent, do nothing
// If they are from different chains, we need to combine...
if (westID != eastID)
mergeChains(node, westID, m);
}
else {
chainID[index(x, y)] = westID;
searchChainsByID(node, westID);
node->add(m);
node->removeLiberty(node->findLiberty(m));
updateLiberty(node, x, y);
added = true;
}
}
if (northID) {
if (added) {
if (northID != eastID && northID != westID)
mergeChains(node, northID, m);
}
else {
chainID[index(x, y)] = northID;
searchChainsByID(node, northID);
node->add(m);
node->removeLiberty(node->findLiberty(m));
updateLiberty(node, x, y);
added = true;
}
}
if (southID) {
if (added) {
if (southID != eastID && southID != westID && southID != northID)
mergeChains(node, southID, m);
}
else {
chainID[index(x, y)] = southID;
searchChainsByID(node, southID);
node->add(m);
node->removeLiberty(node->findLiberty(m));
updateLiberty(node, x, y);
added = true;
}
}
}
// Update opponent liberties
int eastID = (east == victim) * chainID[index(x+1, y)];
int westID = (west == victim) * chainID[index(x-1, y)];
int northID = (north == victim) * chainID[index(x, y+1)];
int southID = (south == victim) * chainID[index(x, y-1)];
if (eastID) {
Chain *node = nullptr;
int nodeIndex = searchChainsByID(node, eastID);
node->removeLiberty(node->findLiberty(m));
if (node->liberties == 0)
captureChain(node, nodeIndex);
}
if (westID && westID != eastID) {
Chain *node = nullptr;
int nodeIndex = searchChainsByID(node, westID);
node->removeLiberty(node->findLiberty(m));
if (node->liberties == 0)
captureChain(node, nodeIndex);
}
if (northID && northID != eastID && northID != westID) {
Chain *node = nullptr;
int nodeIndex = searchChainsByID(node, northID);
node->removeLiberty(node->findLiberty(m));
if (node->liberties == 0)
captureChain(node, nodeIndex);
}
if (southID && southID != eastID && southID != westID && southID != northID) {
Chain *node = nullptr;
int nodeIndex = searchChainsByID(node, southID);
node->removeLiberty(node->findLiberty(m));
if (node->liberties == 0)
captureChain(node, nodeIndex);
}
// Check for a suicide
int selfID = chainID[index(x, y)];
Chain *node = nullptr;
int nodeIndex = searchChainsByID(node, selfID);
if (node->liberties == 0)
captureChain(node, nodeIndex);
// A debugging check
assert(!checkChains());
// Check if p captured any of the other player's stones with move m
/*
doCaptures<true>(victim, coordToMove(x+1, y));
doCaptures<true>(victim, coordToMove(x-1, y));
doCaptures<true>(victim, coordToMove(x, y+1));
doCaptures<true>(victim, coordToMove(x, y-1));
// Check if p suicided with move m
doCaptures<true>(p, coordToMove(x, y));
*/
}
// Performs a capture on a chain and updates the board, adjacent liberties, etc.
// To be called on a chain that has no liberties
void Board::captureChain(Chain *node, int nodeIndex) {
Player victim = node->color;
if (victim == BLACK)
whiteCaptures += node->size;
else
blackCaptures += node->size;
for (int i = 0; i < node->size; i++) {
int rx = getX(node->squares[i]);
int ry = getY(node->squares[i]);
pieces[index(rx, ry)] = EMPTY;
chainID[index(rx, ry)] = 0;
zobristKey ^= zobristTable[zobristIndex(node->color, rx, ry)];
// Add this square to adjacent chains' liberties
int addID = chainID[index(rx+1, ry)];
if (addID
&& addID != node->id) {
Chain *temp = nullptr;
searchChainsByID(temp, addID);
if (temp->findLiberty(coordToMove(rx, ry)) == -1)
temp->addLiberty(coordToMove(rx, ry));
}
addID = chainID[index(rx-1, ry)];
if (addID
&& addID != node->id
&& addID != chainID[index(rx+1, ry)]) {
Chain *temp = nullptr;
searchChainsByID(temp, addID);
if (temp->findLiberty(coordToMove(rx, ry)) == -1)
temp->addLiberty(coordToMove(rx, ry));
}
addID = chainID[index(rx, ry+1)];
if (addID
&& addID != node->id
&& addID != chainID[index(rx+1, ry)]
&& addID != chainID[index(rx-1, ry)]) {
Chain *temp = nullptr;
searchChainsByID(temp, addID);
if (temp->findLiberty(coordToMove(rx, ry)) == -1)
temp->addLiberty(coordToMove(rx, ry));
}
addID = chainID[index(rx, ry-1)];
if (addID
&& addID != node->id
&& addID != chainID[index(rx+1, ry)]
&& addID != chainID[index(rx-1, ry)]
&& addID != chainID[index(rx, ry+1)]) {
Chain *temp = nullptr;
searchChainsByID(temp, addID);
if (temp->findLiberty(coordToMove(rx, ry)) == -1)
temp->addLiberty(coordToMove(rx, ry));
}
}
// Remove this chain since it has been captured
delete node;
chainList.removeFast(nodeIndex);
}