leetcode56.合并区间-java

class Solution {
    public int[][] merge(int[][] intervals) {
        /*
            思路：左区间排序，若intervals[i][0] >= intervals[i-1][1]; 则重叠
            将重叠区间新建放入res数组里，没重叠则放入原数组 
        */
        List<int[]> res = new LinkedList<>();
        Arrays.sort(intervals, (a,b) -> Integer.compare(a[0], b[0]));
        //initial start 是最小左边界
        int start = intervals[0][0];
        int rightmostRightBound = intervals[0][1];
        for(int i = 1; i < intervals.length; i++) {
             //如果左边界大于最大右边界
             if(intervals[i][0] > rightmostRightBound) {//没重叠
                //加入区间 并且更新start
                res.add(new int[]{start, rightmostRightBound});
                start = intervals[i][0];
                rightmostRightBound = intervals[i][1];
             } else {
                //更新最大右边界
                rightmostRightBound = Math.max(rightmostRightBound, intervals[i][1]);
             }
        }
        res.add(new int[]{start, rightmostRightBound});
        return res.toArray(new int[res.size()][]);
    }
}