题解 | #括号序列#

注意边界值处理

class Solution {
public:
    /**
     * 
     * @param s string字符串 
     * @return bool布尔型
     */
    bool isValid(string s) {
        // write code here
        if(!s.length()){
            return false;
        }

        stack<char> parantheses;
        parantheses.push(s[0]);
        for(int i = 1; i<s.length();i++){

            if(parantheses.empty()){
                parantheses.push(s[i]);          
                continue;
            }
            char top_char = parantheses.top();

            if(top_char =='['&& s[i] ==']'){
                parantheses.pop();
                continue;
            }else if(top_char =='('&& s[i] ==')'){
                parantheses.pop();
                continue;
            } else if(top_char =='{'&& s[i] =='}'){
                parantheses.pop();
                continue;
            }
            parantheses.push(s[i]);          

        }

        return parantheses.size()==0?true:false;


    }
};