有一种栈，这种栈是按数组索引减小的方向增长的 在这个栈模型中，索引top在每次push索引操作后减小，而在pop操作后则增大。用此模型实现stack类模板-There is a stack, this stack is reduced by the array index in the stack direction of the growth model, the index top index in each push operation is reduced, and after th