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.size() < 1) return intervals;
        intervals.sort(new Comparator<Interval>() {
            @Override
            public int compare(Interval i1, Interval i2) {
                if (i1.start != i2.start) {
                    return Integer.compare(i1.start, i2.start);
                }
                return Integer.compare(i1.end, i2.end);
            }
        });
        // write code here
        ArrayList<Interval>list = new ArrayList<>();
        if (intervals.get(0).start == 0 && intervals.get(0).end == 0 &&
                intervals.get(1).start > 0) {
            Interval interval = new Interval(0, 0);
            list.add(interval);
        }
        int min = 0;
        int max = 0;
        for (int i = 0; i < intervals.size(); i++) {
            if (min == 0 && max == 0) {
                min = intervals.get(i).start;
                max = intervals.get(i).end;
                continue;
            }
            if (intervals.get(i).start > max) {
                Interval interval = new Interval(min, max);
                list.add(interval);
                min = 0;
                max = 0;
                i--;
                continue;
            }
            if (intervals.get(i).start <= max && intervals.get(i).end > max) {
                max = intervals.get(i).end;
            }
            if (intervals.get(i).start < min && intervals.get(i).end > min) {
                min = intervals.get(i).start;
            }
        }
        Interval interval = new Interval(min, max);
        list.add(interval);
        return list;
    }
}