栈

const int maxn = 1e5+5;//栈的最大容量
int sta[maxn]; //栈的存储空间
int head = 0;  //栈顶

void push(int n){ 
    sta[head++] = n; //插入,为什么是top++,不是++top?
}

void pop(){
    return top--; 
}

int top() {
    return sta[top-1];
}

bool empty() {
    return top == 0;
}

template<typename T = int,int siz = maxn>
struct mystack{
    T sta[siz+5];
    int head = 0;

    void clear() { head = 0;}

    void push(T a) { sta[head++] = a;}

    void pop(){head--;}

    T top() { return sta[head-1];}

    bool empty() { return head == 0;}

    int size() { return head;}
};