Task with braces, brackets and parenthesis

Question

Task is to check if given string contains balanced sets of {}, [] and ().

For example, check(\"{[}]\") must return

Answer 1

Please tell me what is wrong with my code it's always giving NO

string isBalanced(string s) {
stack comp;
char temp;
int i;
for(i=s.size()-1;(s[i]=='}' ) || (s[i]==')' ) || (s[i]==']');i--)
{
    comp.push(s[i]);
}

if(comp.size()!=i+1)
return ("NO");

while(!comp.empty() && i>=0)
{
    temp=comp.top();
    if(temp!=s[i])
    return ("NO");
    comp.pop();
    i--;
}

return("YES");
}