代码随想录：有效的括号

代码随想录：有效的括号

class Solution {
public:
    bool isValid(string s) {
        stack<char> a;
        for (char target : s) {
            if (target == '(' || target == '{' || target == '[') {
                a.push(target);
            } else if (!a.empty() && target == ')') {
                if (a.top() == '(')
                    a.pop();
                else
                    return false;
            } else if (!a.empty() && target == '}') {
                if (a.top() == '{')
                    a.pop();
                else
                    return false;
            } else if (!a.empty() && target == ']') {
                if (a.top() == '[')
                    a.pop();
                else
                    return false;
            }else{
                return false;
            }
        }
        if (a.empty()) {
            return true;
        } else {
            return false;
        }
    }
};