class Solution {
public:
    bool isValid(string s) {
        stack<char> st;
        unordered_map<char,char> mapping = {{')','('}, {'}','{'}, {']','['}};
        for(char c: s){
                if(mapping.find(c) == mapping.end()) st.push(c);
                else if(!st.empty() && mapping[c] == st.top()) st.pop();
                else return false;

        }
        return st.empty();



    }
};