LeetCode:Valid Parentheses

Given a string containing just the characters

'('

,

')'

,

'{'

,

'}'

,

'['

and

']'

, determine if the input string is valid.

The brackets must close in the correct order,

"()"

and

"()[]{}"

are all valid but

"(]"

and

"([)]"

are not.

class Solution {
public:
bool isValid(string s) {
stack<char> cstack;
string left="({[";
string right=")}]";

for(auto c:s)
{
if(left.find(c)!=s.npos)
cstack.push(c);
else if(cstack.empty()||cstack.top()!=left[right.find(c)])
return false;
else
cstack.pop();
}

return cstack.empty();

}
};