Solution.java

/**
 * 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 Solution {
    public List<Interval> insert(List<Interval> intervals, Interval newInterval) {
        int s = newInterval.start;
        int e = newInterval.end;
        if (intervals.size()==0) {
            intervals.add(newInterval);
            return intervals;
        }
        List<Interval> answerList = new ArrayList<Interval>();
        int ns=0;
        int ne=0;
        boolean beginFlag=true;
        boolean endFlag=true;
        for (int i = 0; i < intervals.size(); i++) {
            if (endFlag&&beginFlag) {
                if (intervals.get(i).start>=s) {
                    ns=s;
                    beginFlag=false;
                }else if (intervals.get(i).end>=s) {
                    if (intervals.get(i).end>=e) {
                        endFlag=false;
                    }else {
                        ns=intervals.get(i).start;
                        beginFlag=false;
                    }
                }
            }
            if (endFlag&&!beginFlag) {
                if (intervals.get(i).start>e) {
                    ne=e;
                    answerList.add(new Interval(ns,ne));
                    endFlag=false;
                    beginFlag=true;
                }else if(intervals.get(i).start==e){
                    ne=intervals.get(i).end;
                    answerList.add(new Interval(ns,ne));
                    endFlag=false;
                    beginFlag=true;
                    continue;
                }else if(intervals.get(i).end>=e){
                    ne=intervals.get(i).end;
                    answerList.add(new Interval(ns,ne));
                    endFlag=false;
                    beginFlag=true;
                    continue;
                }else if(i==intervals.size()-1){
                    ne=e;
                    answerList.add(new Interval(ns,ne));
                    return answerList;
                }
            }
            if (beginFlag) {
                answerList.add(intervals.get(i));
            }
        }
        if (endFlag) {
            answerList.add(newInterval);
        }
        return answerList;
    }
}