public int intersectionSizeTwo(int[][] intervals) {

int res=0;

List<int[]> list = new ArrayList<>();

//依据首元素排序

Arrays.sort(intervals, (o1, o2) -> o1[0]-o2[0]);

//前后求交集

for (int i = 1; i < intervals.length ; i++) {

if (intervals[i][0] <= intervals[i-1][1]){

intervals[i][0] = intervals[i][0] < intervals[i-1][0] ? intervals[i-1][0] : intervals[i][0];

intervals[i][1] = intervals[i][1] < intervals[i-1][1] ? intervals[i][1] : intervals[i-1][1];

}else{ //重叠区间合并完毕

list.add(intervals[i-1]);

}

//区间末尾是最后一个合并完成的区间

if (i==intervals.length-1){

list.add(intervals[i]);

}

}

return res;

}

public static void main(String[] args) {

new leetcode757().intersectionSizeTwo(new int[][]{

{1,2},{2,3},{3,4},{4,5}

});

}