Merge Intervals

MergeIntervals.java

public class MergeIntervals {
 
 public List<Interval> merge(List<Interval> intervals) {
    
    List<Interval> mergedIntervals = new ArrayList<>();
    
    if(intervals == null || intervals.size() == 0) 
        return mergedIntervals;
    
    int n = intervals.size();
    
    if(n == 1) 
        return intervals;

    Collections.sort(intervals, new IntervalComparator());
    
    Interval current = intervals.get(0);
    
    for(int i = 1; i < n; ++i){
        
        Interval next = intervals.get(i);
        if(next.start <= current.end)
            current.end = Math.max(current.end, next.end);
        
        else{
            mergedIntervals.add(current);
            current = next;
        }
    }
    
    mergedIntervals.add(current);

    return mergedIntervals;
}



  public class Interval {
    public int start;
    public int end;
    Interval() { start = 0; end = 0; }
    Interval(int s, int e) { start = s; end = e; }
  }


public class IntervalComparator implements Comparator<Interval>{
    
    public int compare(Interval first, Interval second){
        
        return first.start - second.start;
    }
} 
  
}