1 class Solution {
2 public:
3 /**
4 * @param s A string
5 * @return whether the string is a valid parentheses
6 */
7 bool isValidParentheses(string& s) {
8 // Write your code here
9 stack<char> parens;
10 for (int i = 0; i < (int)s.length(); i++) {
11 if (s[i] == '(' || s[i] == '[' || s[i] == '{')
12 parens.push(s[i]);
13 else if (parens.empty() || !match(s[i], parens.top()))
14 return false;
15 else parens.pop();
16 }
17 return parens.empty();
18 }
19 private:
20 bool match(char s, char t) {
21 if (s == ')') return t == '(';
22 if (s == ']') return t == '[';
23 if (s == '}') return t == '{';
24 }
25 };
