class Solution {
public:
    bool isValid(string s){
        stack<char>S;for(auto c:s)
            if(S.empty())S.push(c);
            else{char C=S.top();
                if((C=='('&&c==')')||(C=='['&&c==']')||
                   (C=='{'&&c=='}'))S.pop();
                else S.push(c);
            }
        return S.empty();
    }
};

给出一个简洁的题解