LeetCode 57. Insert Interval - (Problem Link - https://leetcode.com/problems/insert-interval/) Given a set of non-overlapping intervals, insert a new interval into the intervals (merge if necessary). You may assume that the intervals were initially sorted according to their start times. Example 1: Given intervals [1,3],[6,9], insert and merge [2…

InsertInterval.java

/**
LeetCode 57. Insert Interval
Given a set of non-overlapping intervals, insert a new interval into the intervals (merge if necessary).
You may assume that the intervals were initially sorted according to their start times.

Example 1:
Given intervals [1,3],[6,9], insert and merge [2,5] in as [1,5],[6,9].

Example 2:
Given [1,2],[3,5],[6,7],[8,10],[12,16], insert and merge [4,9] in as [1,2],[3,10],[12,16].
This is because the new interval [4,9] overlaps with [3,5],[6,7],[8,10].
*/

/**
 * Definition for an interval.
 * public class Interval {
 *     int start;
 *     int end;
 *     Interval() { start = 0; end = 0; }
 *     Interval(int s, int e) { start = s; end = e; }
 * }
 */
public class InsertInterval {
    public List<Interval> insert(List<Interval> intervals, Interval newInterval) {
        List<Interval> result = new ArrayList<Interval>();
        if(intervals.isEmpty()){
            result.add(newInterval);
            return result;
        }
        intervals.add(newInterval);
        Collections.sort(intervals, new Comparator<Interval>(){
            public int compare(Interval i1, Interval i2){
                return i1.start - i2.start;
            }
        });
        Interval current = intervals.get(0);
        for(int i = 1; i < intervals.size(); i++){
            // Merge if overlap
            if(current.end >= intervals.get(i).start){
                if(intervals.get(i).end > current.end){
                    current.end = intervals.get(i).end;
                }
            }
            // Add to result and start a new one
            else{
                result.add(current);
                current = intervals.get(i);
            }
        }
        // Add back the last captured interval to result
        result.add(current);
        return result;
    }
}