copy method

@override GridBFSState copy()

Implementation

@override
GridBFSState copy() {
  return GridBFSState(
    start: start,
    target: target,
    grid: List.generate(grid.length, (i) => List.from(grid[i])),
    parents: HashMap.from(parents),
    dirs: List.from(dirs),
    open: Queue.from(open),
    status: status,
  );
}