LeetCode#20 Valid Parentheses

class Solution {
public:
bool isValid(string s) {
if(s.size()%2 != 0)
return false;

stack<char> c;
for(int i = 0; i < s.size(); i++)
{
//cout<<c.empty()<<endl;
if(c.empty())
c.push(s[i]);
else
{
//cout<<c.top()<<endl;
if(c.top()!='[' && s[i] == ']' || c.top()!='{' && s[i] == '}' || c.top()!='(' && s[i] == ')')
return false;
if(c.top()=='[' && s[i] == ']' || c.top()=='{' && s[i] == '}' || c.top()=='(' && s[i] == ')')
c.pop();
else
c.push(s[i]);

}
}
if(c.empty())
return true;
else
return false;
}
};