leetcode valid parentheses

class  {
public:
    bool isValid(string s) {
        stack<char> ps;
        for(int i = 0; i < s.size(); ++i) {
            if(s[i] == '(' || s[i] == '{' || s[i] == '[') {
                ps.push(s[i]);
            }else {
                if(ps.empty()) return false;
                char top_v = ps.top();
                if((s[i] == ')' && top_v == '(') || (s[i] == '}' && top_v == '{') || (s[i] == ']' && top_v == '[')) {
                    ps.pop();
                }else {
                    return false;
                }
            }
        }
        if(!ps.empty()) {
            return false;
        }
        return true;
    }
};