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// @Title: 合并区间 (Merge Intervals)
// @Author: 15816537946@163.com
// @Date: 2020-11-29 14:27:46
// @Runtime: 12 ms
// @Memory: 4.6 MB
func merge(intervals [][]int) [][]int {
	if len(intervals) <= 1 {
		return intervals
	}

	sort.Sort(Its(intervals))
	res := make([][]int, 0, len(intervals))
	tmp := intervals[0]
	for i := range intervals {
		if intervals[i][0] <= tmp[1] {
			// merge
			tmp[1] = max(intervals[i][1], tmp[1])
		} else {
			res = append(res, tmp)
			tmp = intervals[i]
		}
	}
	res = append(res, tmp)
	return res
}

func max(a, b int) int {
	if a > b {
		return a
	}
	return b
}

type Its [][]int

func (t Its) Less(i, j int) bool {
	return t[i][0] < t[j][0]
}

func (t Its) Swap(i, j int) {
	t[i], t[j] = t[j], t[i]
}

func (t Its) Len() int {
	return len(t)
}