Stack

代码说明：

  由于栈也是线性表，因此线性表的存储结构对栈也适用，通常栈有顺序栈和链栈两种存储结构，这两种存储结构的不同，则使得实现栈的基本运算的算法也有所不同。(Because the stack is also a linear table, the storage structure of the linear table is also applicable to the stack, usually the stack has two kinds of storage structures: sequence stack and chain stack. The two different storage structures make the algorithms of the basic operation of the stack different.)