[C++] calculate round for start and finish time respectively.
\nclass Solution {\npublic:\n    int numberOfRounds(string startTime, string finishTime) {\n        int startHour, startMin, stopHour, stopMin;\n        \n     
```\nclass Solution {\npublic:\n    int numberOfRounds(string startTime, string finishTime) {\n        int startHour, startMin, stopHour, stopMin;\n        \n        startHour = stoi(startTime.substr(0, 2));\n        startMin = stoi(startTime.substr(3, 2));\n        stopHour = stoi(finishTime.substr(0, 2));\n        stopMin = stoi(finishTime.substr(3, 2));\n        \n        int start = startHour * 60 + startMin;\n        int stop = stopHour * 60 + stopMin;\n        \n        if (start > stop) {\n            stop += 24 * 60;\n        }\n        \n        start = (start / 15) + (start % 15 > 0);\n        stop /= 15;\n        \n        return max(stop - start, 0);\n    }\n};\n```
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