Java O(1) 100% faster
\nclass Solution {\n    public int numberOfRounds(String startTime, String finishTime) {\n        Integer startHH = Integer.parseInt(startTime.substring(0,2));\
```\nclass Solution {\n    public int numberOfRounds(String startTime, String finishTime) {\n        Integer startHH = Integer.parseInt(startTime.substring(0,2));\n        Integer startMM = Integer.parseInt(startTime.substring(3));\n        Integer finishHH = Integer.parseInt(finishTime.substring(0,2));\n        Integer finishMM = Integer.parseInt(finishTime.substring(3));\n        \n        int start = startHH*60 +startMM;\n        int end = finishHH*60 +finishMM;\n        if (start > end) {\n           end += 24*60;\n        }\n        \n        return (int) Math.floor(end / 15.00) - (int) Math.ceil(start / 15.00);\n    }\n}\n```
['Java']