LeetCode: Merge Intervals

comparator的写法。

Collections.sort与Arrays.sort的区别。

Arrays.sort只应用于arrays。LinkedList，ArrayList要用collections.sort。

都可以使用comparator。

 

public class Solution {
    public static ArrayList<Interval> merge(ArrayList<Interval> intervals) {
        ArrayList<Interval> result = new ArrayList<Interval>();
        if (intervals.size() == 0) return result;
        Collections.sort(intervals, new comparator());
        
        result.add(intervals.get(0));
        
        for (int i=1; i<intervals.size(); i++) {
            Interval in = intervals.get(i);
            Interval last = result.get(result.size()-1);
            
            if (in.start<=last.end) {
                if (in.end > last.end)
                    last.end = in.end;
            }
            else {
                result.add(in);
            }
        }
        
        return result;
    }
    
    static class comparator implements Comparator<Interval> {
        public int compare(Interval a, Interval b) {
            // TODO Auto-generated method stub
            return a.start - b.start;
        }
    }
}