Merge Intervals

/**
* 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> merge(List<Interval> intervals) {
List<Interval> res = new LinkedList<>();
if (intervals == null) {
throw new IllegalArgumentException(" ");
}
if (intervals.size() == 0) {
return res;
}
Collections.sort(intervals, new Comparator<Interval>(){
@Override
public int compare(Interval a, Interval b) {
if (a.start != b.start) {
return a.start - b.start;
} else {
return a.end - b.end;
}
}
});
Interval prev = intervals.get(0);
for (int i = 1; i < intervals.size(); i++) {
Interval cur = intervals.get(i);
if (cur.start > prev.end) {
res.add(prev);
prev = cur;
} else {
Interval merge = new Interval(prev.start, Integer.max(prev.end, cur.end));
prev = merge;
}
}
res.add(prev);
return res;
}
}