A.放入元素到棧頂 B.放入元素到棧底 C.返回并刪除棧頂元素 D.清空棧
A.120 B.121 C.132 D.36
A.左端(下標0端)放棧底,右端放棧頂 B.棧頂 C.棧底 D.左端(下標0端)放棧頂,右端放棧底