Given a collection of intervals, merge all overlapping intervals.

Example 1:

Input: [[1,3],[2,6],[8,10],[15,18]]
Output: [[1,6],[8,10],[15,18]]
Explanation: Since intervals [1,3] and [2,6] overlaps, merge them into [1,6].

Example 2:

Input: [[1,4],[4,5]]
Output: [[1,5]]
Explanation: Intervals [1,4] and [4,5] are considered overlapping.

题目链接：https://leetcode.com/problems/merge-intervals/

题目分析：sort完模拟即可

9ms，时间击败94.4%

/**
 * 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; }
 * }
 */
class Solution {
    public List<Interval> merge(List<Interval> intervals) {
        int sz = intervals.size();
        List<Interval> ans = new ArrayList<>();
        if (sz == 0) {
            return ans;
        }

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

        int st = intervals.get(0).start;
        int ed = intervals.get(0).end;
        int pos = 0;
        while (pos < sz) {
            while (pos < sz && intervals.get(pos).start <= ed) {
                if (intervals.get(pos).end > ed) {
                    ed = intervals.get(pos).end;
                }
                pos++;
            }
            ans.add(new Interval(st, ed));
            if (pos < sz) {
                st = intervals.get(pos).start;
                ed = intervals.get(pos).end;
            }
        }
        return ans;
    }
}