题解 | #合并区间#

import java.util.*;

/*
 * public class Interval {
 *   int start;
 *   int end;
 *   public Interval(int start, int end) {
 *     this.start = start;
 *     this.end = end;
 *   }
 * }
 */

public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     *
     * @param intervals Interval类ArrayList
     * @return Interval类ArrayList
     */
    public ArrayList<Interval> merge (ArrayList<Interval> intervals) {
        if (intervals.isEmpty()) return intervals;
        intervals.sort((v1, v2)->  v1.start - v2.start);
        // write code here
        ArrayList<Interval> res = new ArrayList<>();
        int begin = intervals.get(0).start, end = intervals.get(0).end;
        for (int i = 1; i < intervals.size(); i++) {
            Interval interval = intervals.get(i);
            if (end >= interval.start) {
                end = Math.max(end, interval.end);
            } else {
                res.add(new Interval(begin, end));
                begin = interval.start;
                end = interval.end;
            }
        }
        res.add(new Interval(begin, end));
        return res;
    }
}