Merge Intervals

题目

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].

class Solution {
    public List merge(List intervals) {
        if(intervals.size() <= 1) return intervals;
        List ans = new LinkedList();
        // sort by start time
        Collections.sort(intervals, new Comparator() {
            public int compare(Interval c1, Interval c2) {
                if (c1.start > c2.start) return 1;
                if (c1.start < c2.start) return -1;
                return 0;
            }
        });

        int left = 0, right;
        while(left < intervals.size()) {
            Interval i1 = intervals.get(left);
            for(right = left + 1; right < intervals.size(); right++) {
                Interval i2 = intervals.get(right);
                if(i1.end < i2.start) break;
                i1.end = Math.max(i1.end, i2.end);
            }
            ans.add(i1);
            left = right;
        }
        return ans;
    }
}