Insert Interval & Merge intervals

Insert intervals

Given a non-overlapping interval list which is sorted by start point.

Insert a new interval into it, make sure the list was still in order and non-overlapping (merge intervals if neces Sary).

Example

Insert [2, 5] into [[up], [5,9]], we get [[1,9]].

Insert [3, 4] into [[up], [5,9]], we get [[up], [3,4], [5,9]].

Analysis:

Create a new array list, insert the smaller interval in the new array and use a counter to keep track of the total number of smaller intervals. If we find an interval overlapping with the new one, we need to the change the start and end.

1 /**2 * Definition of Interval:3 * Public classs Interval {4 * int start, end;5 * Interval (int start, int end) {6 * This.start = start;7 * this.end = end;8  *     }9  */Ten  One classSolution { A     /** - * Insert newinterval into intervals. - * @param intervals:sorted interval list. the * @param newinterval:a new interval. - * @return: A new sorted interval list. -      */ -      +      Publicarraylist<interval> Insert (arraylist<interval>intervals, Interval newinterval) { -         if(NewInterval = =NULL|| intervals = =NULL) { +             returnintervals; A         } at  -arraylist<interval> results =NewArraylist<interval>(); -         intInsertpos =0; -  -          for(Interval interval:intervals) { -             if(Interval.end <Newinterval.start) { in Results.add (interval); -insertpos++; to}Else if(Interval.start >newinterval.end) { + Results.add (interval); -}Else { theNewinterval.start =math.min (Interval.start, newinterval.start); *Newinterval.end =Math.max (Interval.end, newinterval.end); $             }Panax Notoginseng         } -  the Results.add (Insertpos, newinterval); +         returnresults; A  the     } +}

Merge intervals

Given a collection of intervals, merge all overlapping intervals.

Example

Given intervals = merged intervals:

[                     [  [1, 3],               [1, 6],  [2, 6],      =>       [8, 10],  [8, 10],              [15, 18]  [15, 18]            ]]

Analyze:

Sort first, then merge intervals if they overlap.

1 /**2 * Definition of Interval:3 * public class Interval {4 * int start, end;5 * Interval (int start, int end) {6 * This.start = start;7 * this.end = end;8  *     }9  */Ten  One classSolution { A     /** - * @param intervals, a collection of intervals - * @return: A new sorted interval list. the      */ -      PublicList<interval> Merge (list<interval>list) { -          -         if(List = =NULL|| List.size () <=1) { +             returnlist; -         } +          ACollections.sort (list,NewComparator<interval>(){ at              Public intCompare (Interval A, Interval b) { -                 returnA.start-B.start; -         }}); -          -          for(inti =1; I < list.size (); i++) {   -             //No intersection in             if(overlap (List.Get(i), list.GetI1))) {  -List.GetI1). Start = Math.min (list.Get(i). Start, list.GetI1). Start);  toList.GetI1). End = Math.max (list.Get(i). end, list.GetI1). end);  + List.remove (i); -i--; the             } *         }   $         returnlist;Panax Notoginseng     } -      the boolean overlap (Interval i1, Interval i2) { +         returnMath.max (I1.start, I2.start) <=math.min (I1.end, i2.end);  A     }  the}

Insert Interval & Merge intervals