An integer interval [a, b] (for integers a < b) is a set of all consecutive integers from a to b, including a and b.
Find the minimum size of a set S such that for every integer interval A in intervals, the intersection of S with A has a size of at least two.
Example 1:
Input: intervals = [[1,3],[1,4],[2,5],[3,5]]
Output: 3
Explanation: Consider the set S = {2, 3, 4}. For each interval, there are at least 2 elements from S in the interval.
Also, there isn't a smaller size set that fulfills the above condition.
Thus, we output the size of this set, which is 3.
Example 2:
Input: intervals = [[1,2],[2,3],[2,4],[4,5]]
Output: 5
Explanation: An example of a minimum sized set is {1, 2, 3, 4, 5}.
Constraints:
1 <= intervals.length <= 3000intervals[i].length == 20 <= ai < bi <= 108