【学习版】

【C语言】

【C++】

#include<iostream>

class MyStack {
public:
	struct Node {
		char val;
		Node* prev;
		Node* next;
		Node(char x) :val(x), prev(NULL),next(NULL) {};
	};
	MyStack() {
		base = new Node('0');
		top = base;
	}
	bool empty() {
		return top == base;
	}
	void push(int x) {
		Node* newNode = new Node(x);
		top->next = newNode;
		newNode->prev = top;
		top = top->next;
	}
	void pop() {
		Node* tmp = top;
		top = top->prev;
		delete tmp;
	}
	char Top() {
		return top->val;
	}
private:
	Node* base;
	Node* top;
};
int main() {
	std::string s;
	MyStack stk;
	std::cin >> s;
	for (int i = 0; i < s.size(); i++) {
		if (!stk.empty() && s[i] == ')') {
			if (stk.Top() == '(') {
				stk.pop();
				continue;
			}
		}
		if (!stk.empty() && s[i] == ']') {
			if (stk.Top() == '[') {
				stk.pop();
				continue;
			}
		}
		stk.push(s[i]);
	}
	if (stk.empty()) {
		std::cout << "YES";
	}
	else std::cout << "NO";
	return 0;
}

【STL】

#include<iostream>
#include<stack>
void solve() {
	std::string s;
	std::stack<char> stk;
	std::cin >> s;
	for (int i = 0; i < s.size(); i++) {
		if (!stk.empty()&&s[i] == ')') {
			if (stk.top() == '(') {
				stk.pop();
				continue;
			}
		}
		if (!stk.empty()&&s[i] == ']') {
			if (stk.top() == '[') {
				stk.pop();
				continue;
			}
		}
		stk.push(s[i]);
	}
	if (stk.empty()) {
		std::cout << "YES";
	}
	else std::cout << "NO";
	return;
}
int main() {
	solve();
	return 0;
}