Parenthesis Checker

#include<bits/stdc++.h>
using namespace std;

class Solution
{
    public:
    bool ispar(string x)
    {
        stack<char>s;
        char y;
        for(int i=0;i<x.length();i++)
        {
            if (x[i] == '(' || x[i] == '[' || x[i] == '{') 
            {
                s.push(x[i]);
                continue;
            }
            if(s.empty())
                return false;
            switch(x[i])
            {
                case ')':
                    y = s.top();
                    s.pop();
                    if(y == '{' || y == '[')
                        return false;
                    break;
                case '}':
                    y = s.top();
                    s.pop();
                    if(y == '(' || y == '[')
                        return false;
                    break;
                case ']':
                    y = s.top();
                    s.pop();
                    if(y == '(' || y == '{')
                        return false;
                    break;
            }
        }
        return (s.empty());
    }

};

int main()
{
   int t;
   string a;
   cin>>t;
   while(t--)
   {
       cin>>a;
       Solution obj;
       if(obj.ispar(a))
        cout<<"balanced"<<endl;
       else
        cout<<"not balanced"<<endl;
   }
}