LintCode: Valid Parentheses

C++

stack<char|int|string>, push(), pop(), top(), empty(), size()

class Solution {
public:
    /**
     * @param s A string
     * @return whether the string is a valid parentheses
     */
    bool isValidParentheses(string& s) {
        // Write your code here
        stack<char> sta;
        for (int i = 0; i < s.size(); i++) {
            if (s[i] == '(' || s[i] == '{' || s[i] == '[') {
                sta.push(s[i]);
                continue;
            }
            char top = sta.top();
            sta.pop();
            if (s[i] == ')' && top != '(') return false;
            if (s[i] == ']' && top != '[') return false;
            if (s[i] == '}' && top != '{') return false;
        }
        return sta.empty();
    }
};