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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 size at least 2.
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}.
Note:
intervals
will have length in range [1, 3000]
.
intervals[i]
will have length 2
, representing some integer interval.
intervals[i][j]
will be an integer in [0, 10^8]
.
[Greedy]