[Leetcode] Merge Intervals

Given a collection of intervals, merge all overlapping intervals.

For example,
Given [1,3],[2,6],[8,10],[15,18],
return [1,6],[8,10],[15,18].

Solution:

/**
 * 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 {
    static public class MyCompare implements Comparator<Interval> {
        @Override
        public int compare(Interval o1, Interval o2) {
            // TODO Auto-generated method stub
            if (o1.start != o2.start)
                return o1.start < o2.start ? -1 : 1;
            else if (o1.end != o2.end)
                return o1.end < o2.end ? -1 : 1;
            else
                return 0;
        }
    }

    public List<Interval> merge(List<Interval> intervals) {
        List<Interval> result = new ArrayList<Interval>();
        
        if (intervals.size() == 0)
            return result;
        if (intervals.size() == 1)
            return intervals;
        
        Collections.sort(intervals, new MyCompare());
        Interval last=intervals.get(0);
        int N=intervals.size();
        for(int i=1;i<N;++i){
            if(intervals.get(i).start>last.end){
                result.add(new Interval(last.start,last.end));
                last=intervals.get(i);
            }else{
                last.end=Math.max(intervals.get(i).end, last.end);
            }
        }
        result.add(last);
        return result;
    }
}