题解 | #括号序列#

class Solution {
public:
    /**
     * 
     * @param s string字符串 
     * @return bool布尔型
     */
    bool isValid(string s) {
        // write code here
        // 建立hash映射每个括号的值
        stack<char> a;
        map<char,int> mp;
        mp['('] = 1;
        mp[')'] = 4;
        mp['['] = 2;
        mp[']'] = 5;
        mp['{'] = 3;
        mp['}'] = 6;
        for(int i = 0; i < s.length(); i++) {
            auto str = s[i];
            if(mp[str] >= 1 && mp[str] <= 3)
                a.push(str);
            else {
                if(a.empty())
                    return false;
                auto t = a.top();
                if(mp[str] - mp[t] != 3)
                    return false;
                a.pop();
            }
        }
        if(a.size())
            return false;
        return true;
    }
};