For Humans Only , Java O(1)
```\nclass Solution {\n    public int numberOfRounds(String startTime, String finishTime) {\n        \n        //minutes start , finish\n        int start = Int
```\nclass Solution {\n    public int numberOfRounds(String startTime, String finishTime) {\n        \n        //minutes start , finish\n        int start = Integer.parseInt(startTime.split(":")[1]);\n        int finish = Integer.parseInt(finishTime.split(":")[1]);\n        int ans=0;\n        //start : 01:40\n        //result : 2\n        ans += getrounds(start);\n        \n         //finish : 02:51\n        //result : 3\n        ans += getendrounds(finish);\n        \n        //hours start,finish\n         int hstart = Integer.parseInt(startTime.split(":")[0]);\n         int hfinish = Integer.parseInt(finishTime.split(":")[0]);\n        \n        \n        //for case : start 20:16 finish 20:45\n        if(hfinish==hstart && start<finish ){\n            ans = getsame(start,finish);\n        }\n        //for case : start 20:56 finish 23:15\n        else if(hfinish>hstart)\n            ans += (hfinish- (hstart+1))*4;\n        //for case : start 00:01 finish 00:00  || start 23:56 finish 23:15 || start 20:00 finish 01:15\n        else{\n            ans += (24- (hstart+1))*4;\n            ans += (hfinish)*4;\n        }\n            \n        return ans;\n        \n    }\n    \n    int getrounds(int start){\n         int ans=0;\n        if(start==0)\n            ans += 4;\n        else if(start>0 && start<=15)\n            ans += 3;\n        else if(start>15 && start<=30)\n            ans += 2;\n        else if(start>30 && start<=45)\n            ans += 1;\n        \n        return ans;\n    }\n    int getendrounds(int end){\n         int ans=0;\n        if(end>=45)\n            ans += 3;\n        else if(end>=30)\n            ans += 2;\n        else if(end>=15)\n            ans += 1;\n        \n        return ans;\n    }\n    int getsame(int start, int end){\n        \n          if(end>=45)\n              end=45;\n          else if(end>=30)\n            end=30;\n          else if(end>=15)\n            end=15;\n        \n         if(start>0 && start<=15)\n              start=15;\n          else if(start>15 && start<=30 )\n            start=30;\n          else if(start>30)\n            start=45;\n    \n        if(end-start>0)\n            return (end-start)/15;\n        else\n            return 0;\n    }\n}
[]