Poison

56. Merge Intervals

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class Solution {
    public int[][] merge(int[][] intervals) {
        // 只需按 start 排序
        Arrays.sort(intervals, Comparator.comparingInt(o -> o[0]));

        List<int[]> intervalList = new ArrayList<>();
        intervalList.add(Arrays.copyOf(intervals[0], 2));
        for (int i = 1; i < intervals.length; i++) {
            int[] pervInterval = intervalList.get(intervalList.size() - 1);
            if (intervals[i][0] <= pervInterval[1]) {
                pervInterval[1] = Math.max(pervInterval[1], intervals[i][1]);
            } else {
                intervalList.add(Arrays.copyOf(intervals[i], 2));
            }
        }

        return intervalList.toArray(new int[0][]);
    }
}
Reference

56. Merge Intervals