leetcode129valid-parentheses

"["

false

"[]"

true

class Solution {
public:
    /**
     * 
     * @param s string字符串 
     * @return bool布尔型
     */
    bool isValid(string s) {
        // write code here
        int len=s.size();
        stack <char> sta;
        for (int i=0;i<len;i++){
            if (s[i]==‘(‘)sta.push(‘)‘);
            else if (s[i]==‘[‘) sta.push(‘]‘);
            else if (s[i]==‘{‘)sta.push(‘}‘);
            else if (sta.empty())return false;
            else if (sta.top()!=s[i])return false;
            else sta.pop();
            
        }
        return sta.empty();
    }
};