A.(19,21,37,5,2) B.(19,21,5,2,37) C.(19,21,5,37,2) D.(19,21,2,5,37)
A.rear=front B.(front+1)%n=rear C.rear+1=front D.(rear+1)%n=front
A.隊列 B.樹 C.棧 D.集合