主要学习下Arrays.sort()排序二维数组。

class Solution {
    public int[][] merge(int[][] intervals) {
        Arrays.sort(intervals, new Comparator<int[]>() {  //先按第一维进行排序
            @Override
            public int compare(int[] o1, int[] o2) {
                return o1[0] - o2[0];
            }
        });

        int newIntervals[][] = new int[intervals.length][2];
        int index  = 0;
        newIntervals[0][0] = intervals[0][0];
        newIntervals[0][1] = intervals[0][1];

        for (int i = 1; i < intervals.length; i++) {
            if(intervals[i][0]>newIntervals[index][1]){
                index ++;
                newIntervals[index][0] = intervals[i][0];
                newIntervals[index][1] = intervals[i][1];
            }
            else if(intervals[i][0]<=newIntervals[index][1] && intervals[i][1]>=newIntervals[index][1]){
                newIntervals[index][1] = intervals[i][1];
            }else{
                continue;
            }
        }

        int array[][]= new int[index+1][2];
        for (int i = 0; i <=index ; i++) {
            array[i][0] = newIntervals[i][0];
            array[i][1] = newIntervals[i][1]; 
        }
        return array;
    }

}