A30002.表达式括号匹配(stk)

珍爱生命，远离STL（虽然我知道栈有点多余）

#include <iostream>
using namespace std;

const int stklim = 114514;
struct stack{
	public:
		void push(int v) {
			if (tp == stklim-1) return;
			tp++;
			stk[tp] = v;
			return;
		}
		void pop(void) {
			if (tp == -1) return;
			stk[tp] = 0;
			tp--;
			return;
		}
		int top(void) {
			if (tp == -1) return 0;
			return stk[tp];
		}
		size_t size(void) {
			return tp+1;
		}
		bool empty(void) {
			return tp == -1;
		}
	private:
		int tp = -1;
		int stk[stklim];
};
stack stk;

int main(){
	char c;
	while (cin >> c){
		if (c=='@') break;
		if (c=='('){
			stk.push(1);
		}else if (c==')'){
			if (stk.empty()){
				cout<<"NO";
				return 0;
			}else {
				stk.pop();
			}
		}
	}
	if(stk.empty())
		cout << "YES";
	else
		cout << "NO";
	return 0;
}