void init(int pid, Coord c, const Map &map){
id = pid;
size_t N = 4*(map.numRows()+map.numCols());
destroy();
front = new Front(N);
frontNew = new Front(N);
nStep = 1;
front->push(c);
map.mark(id, c) = 1;
}
void step(Map &map){
frontNew->clear();
nStep++;
while(!front->empty()){
const Coord &c = front->pop();
for(int dir = DirectionFirst+1; dir != DirectionLast; ++dir){
if (c.canStepTo(static_cast<Direction>(dir), map)){
Coord cNext = c.stepTo(static_cast<Direction>(dir));
if (!map.mark(id, cNext) && !map.isWall(cNext)){
map.mark(id, cNext) = nStep;
frontNew->push(cNext);
}
}
}
}
Front *f = front;
front = frontNew;
frontNew = f;
}
