docs: boolean checkDuplicates(List<List<NodeInfo>> grid ) {
  
  		for (int i = 0; i < listInfo.size; i++) {
  			listInfo.get(i).marked = false;
  		}
  
  		for (int i = 0; i < grid.size(); i++) {
  			List<NodeInfo> list = grid.get(i);
  			for (int j = 0; j < list.size(); j++) {
  				NodeInfo n = list.get(j);
  				if( n.marked )
  					return true;
  				n.marked = true;
  			}
  		}
  		return false;
  	}