Problems with cat and dog queues

Cat dog queue

【 subject 】

Pets 、 The categories of dogs and cats are as follows ：

Implementation of a dog and cat queue structure , Requirements are as follows ：

● Users can call add Methods will cat Class or dog Class to queue ;

● Users can call pollAll Method , Pop up all instances in the queue in the order of entering the queue ;

● Users can call pollDog Method , Queue up dog The instances of the class pop up in the order of entering the queue ;

● Users can call pollCat Method , Queue up cat The instances of the class pop up in the order of entering the queue ;

● Users can call isEmpty Method , Check if there are any in the queue dog or cat Example ;

● Users can call isDogEmpty Method , Check if there are any in the queue dog Class ;

● Users can call isCatEmpty Method , Check if there are any in the queue cat Class .

【 Ideas 】

This question examines the ability to implement special data structures and the ability to design algorithms for special functions .

This is an open type interview question , I hope the readers can have their own realization , Here are a few common design mistakes ：

● cat Queue only cat example ,dog Queue only dog example , And then use a general queue to put all the instances . The reason for the error ：cat、dog And the update of the general queue .

● Using hash table ,key It means a cat Example or dog example ,value Indicates the order in which this instance is queued . The reason for the error ： An instance cannot be queued multiple times