题解 | #有效括号序列#

class Solution {
  public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     *
     * @param s string字符串
     * @return bool布尔型
     */
    bool isValid(string s) {
        // write code here
        if (s.size() <= 1)
            return false;
        stack<char> op;
        char c;
        int f = 0;
        for (int i = 0; i < s.size(); i++) {
            c = s[i];
            if (c == '(' || c == '[' || c == '{')
                op.push(c);
            else if (c == ')' || c == '}' || c == ']') {
                if (op.empty()) {
                    f = 1;
                    break;
                } else {
                    if ((c == ')' && op.top() == '(')
                            || (c == ']' && op.top() == '[')
                            || (c == '}' && op.top() == '{'))
                        op.pop();
                    else {
                        f = 1;
                        op.push(c);
                    }
                }
            }

        }
        if (op.empty() && f == 0)
            return true;
        else
            return false;;
    }
};