區間問題通常需要排序後處理重疊、合併或插入。常見技巧包括按起點排序和掃描線演算法。Notes:大多數區間題的第一步是按起點排序判斷重疊：a.end >= b.start（排序後）合併區間和插入區間是最基本的操作 #56 Merge Intervals #57 Insert Interval #252 Meeting Rooms #253 Meeting Rooms II #352 Data Stream as Disjoint Intervals #435 Non-overlapping Intervals #1288 Remove Covered Intervals #1851 Minimum Interval to Include Each Query