[leetcode] Merge Intervals

from : https://leetcode.com/problems/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].

/**
 * 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) {
		if (null == intervals || 1 >= intervals.size()) {
			return intervals;
		}

		sort(intervals);		
		List<Interval> merged = new ArrayList<Interval>();
		
		Interval p = intervals.get(0);
		for( Interval cur :  intervals) {
			if(cur.start <= p.end) {
				if(cur.end > p.end) {
					p.end = cur.end;
				}
			} else {
				merged.add(p);
				p = cur;
			}
		}
		merged.add(p);
		
		return merged;
	}

	private void sort(List<Interval> intervals) {
		Collections.sort(intervals, new Comparator<Interval>() {
			@Override
			public int compare(Interval a, Interval b) {
				return a.start - b.start;
			}
		});
	}
}