【重点】【区间问题】56.合并区间

题目
注意有个类似的题目：，注意区分。

class Solution {
   
    public int[][] merge(int[][] intervals) {
   
        List<List<Integer>> res = new ArrayList<>();
        Arrays.sort(intervals, (a1, a2) -> {
   
            return a1[0] - a2[0];
        });
        int left = Integer.MAX_VALUE, right = Integer.MIN_VALUE, i = 0;
        while (i < intervals.length) {
   
            left = Math.min(left, intervals[i][0]);
            right = Math.max(right, intervals[i][1]);
            ++i;
            if (i == intervals.length || right < intervals[i][0]) {
   
                res.add(new ArrayList<>(Arrays.asList(left, right)));
                left = Integer.MAX_VALUE;
                right = Integer.MIN_VALUE;
            }
        }

        int[][] resArray = new int[res.size()][2];
        for (i = 0; i < res.size(); ++i) {
   
            resArray[i][0] = res.get(i).get(0);
            resArray[i][1] = res.get(i).get(1);
        }

        return resArray;
    }
}