636. Exclusive Time of Functions

// TODO: need improve!!!
class Log {
public:
    int id;
    bool start;
    int timestamp;
    int comp;   // compasation
    Log() {
        id = 0;
        timestamp = 0;
        comp = 0;
        start = false;
    }
};
class Solution {
public:
    vector<int> exclusiveTime(int n, vector<string>& logs) {
        vector<int> res(n, 0);
        stack<Log> s;
        for (auto &log : logs) {
            auto item = parseLog(log);
            if (item.start)
                s.push(item);
            else {
                int comp = item.timestamp - s.top().timestamp + 1;
                int exTime = item.timestamp - s.top().timestamp + 1 - s.top().comp;
                res[item.id] += exTime;
                s.pop();
                if (!s.empty()) {
                    s.top().comp += comp;
                }
            }
        }
        return res;
    }
    Log parseLog(const string& s) {
        int col1 = s.find(":");
        int col2 = s.find(":", col1 + 1);
        int id = stoi(s.substr(0, col1));
        int time = stoi(s.substr(col2 + 1));
        string state = s.substr(col1 + 1, col2 - col1 - 1);
        
        Log log;
        if (state == "start")
            log.start = true;
        log.id = id;
        log.timestamp = time;
            
        return log;
    }
};