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].

Analysis

• insert newInterval to intervals according to its start value
• Merge if necessary. Merge method copied from question 'Merge Intervals'

Code

public class Solution {
    public List<Interval> insert(List<Interval> intervals, Interval newInterval) {

        //make a copy, otherwise it is invalid to insert newInterval to intervals
        List<Interval> copy = new ArrayList<Interval>(intervals);

        //add newInterval to ordered place according to start value
        int index=0; 
        for (Interval in:copy){
            if (in.start>newInterval.start) break;
            index++;
        }
        copy.add(index, newInterval);


        List<Interval> res = new ArrayList<Interval>();

        //Merge if necessary
        Interval prev = copy.get(0);
        for (Interval inter:copy){
            if (prev.end < inter.start){
                res.add(prev);
                prev = inter;
            }
            else if (prev.end == inter.start || prev.end < inter.end){
                prev = new Interval(prev.start, inter.end);
            }
        }
        res.add(prev);

        return res;
    }
}