力扣678.有效的括号字符串

• 用两个栈分别存’ ( ‘和‘ * ’的下标

  • ‘ ) ’ 与二者匹配
  • 最后将‘ ( ’与 ‘ * ’匹配

•   class Solution {public:bool checkValidString(string s) {stack<int> st1,st2;int n = s.size();for(int i=0;i<n;i++){char c= s[i];if(c == '(')st1.push(i);else if(c == '*')st2.push(i);else{if(!st1.empty())st1.pop();else if(!st2.empty())st2.pop();else    return false;}}while(!st1.empty() && !st2.empty()){int l = st1.top();st1.pop();int r = st2.top();st2.pop();if(l > r)return false;}return st1.empty();}};